Description
There is a bug with the config.txt parser that ignores conditional filters only for hdmi settings, even when the settings are under the [none] filter.

Reproduction Steps

1. Download fresh Raspbian image
2. Update (apt update && apt upgrade -y)
3. Replace config.txt with version listed below (see config.txt)
4. Connect Raspberry Pi to an HDMI display (anything that is not the resolution of hdmi_mode, 640x480 in this example)
5. Boot Raspberry Pi

config.txt:
In reality, [none] should be a filter that evaluates to false (none simulates false)
[none]
hdmi_ignore_edid=0xa5000080
hdmi_force_hotplug=1
hdmi_pixel_encoding=2
hdmi_drive=1
hdmi_group=2
hdmi_mode=4
[all]

Expected Behaviour
Display resolution should match that of the display as the custom HDMI implementations should not run when they are under the [none] filter (nor any filter that evaluates to false).

Actual Behaviour
Custom HDMI options are set and screen has output resolution as specified under the [none] filter (in this example it's 640x480).

System
Models Tested: CM 3B+, 3B+
OS: Raspbian Buster Lite (Fresh install, fully updated)
vcgencmd version: Sep 24 2019 6820edeee4ef3891b95fc01cf02a7abd7ca52f17
rpi-issue: 2019-09-26 80d486687ea77d31fc3fc13cf3a2f8b464e129be, stage2
Kernel Version: 4.19.75-v7+

Also tried this after rpi-update to kernel 4.19.86-v7+

Logs
Output of vcdbg log msg:
001288.733: brfs: File read: /mfs/sd/config.txt
001289.187: brfs: File read: 139 bytes
001321.736: brfs: File read: /mfs/sd/config.txt
001542.160: gpioman: gpioman_get_pin_num: pin DISPLAY_DSI_PORT not defined
001544.267: *** Restart logging
001544.331: brfs: File read: 139 bytes
001551.070: hdmi: HDMI:hdmi_get_state is deprecated, use hdmi_get_display_state instead
001555.067: brfs: File read: /mfs/sd/cmdline.txt
001555.157: Read command line from file 'cmdline.txt':
001555.216: 'console=serial0,115200 console=tty1 root=PARTUUID=6c586e13-02 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait'
001559.852: brfs: File read: 121 bytes
001563.592: brfs: File read: /mfs/sd/bcm2710-rpi-3-b-plus.dtb
001563.655: Loading 'bcm2710-rpi-3-b-plus.dtb' to 0x100 size 0x69ca
001717.610: brfs: File read: 27082 bytes
001720.957: brfs: File read: /mfs/sd/config.txt
003433.319: gpioman: gpioman_get_pin_num: pin EMMC_ENABLE not defined
003534.620: brfs: File read: 139 bytes
003903.243: brfs: File read: /mfs/sd/kernel7.img
003903.307: Loading 'kernel7.img' to 0x8000 size 0x5108a0
003903.376: Device tree loaded to 0x2eff9200 (size 0x6de5)
003905.944: gpioman: gpioman_get_pin_num: pin SDCARD_CONTROL_POWER not defined
005331.235: vchiq_core: vchiq_init_state: slot_zero = 0xfad80000, is_master = 1
005335.580: hdmi: HDMI:hdmi_get_state is deprecated, use hdmi_get_display_state instead
005340.805: TV service:host side not connected, dropping notification 0x00000002, 0x00000002, 0x00000004
009791.047: brfs: File read: 5310624 bytes