What does this implement/fix?

Fixes compilation error on ESP32-C6 (and C5, H2, P4) where SOC_MOD_CLK_APB does not exist in the soc_module_clk_t enum. These newer variants removed the APB clock enum entry — C6 has SOC_MOD_CLK_PLL_F80M instead.

#13908 replaced esp_clk_apb_freq() with esp_clk_tree_src_get_freq_hz(SOC_MOD_CLK_APB, ...) for the PCNT glitch filter calculation. While the esp_clk_tree migration was correct for the RMT components (using RMT_CLK_SRC_DEFAULT), PCNT has no equivalent portable clock source enum.

This reverts the pulse_counter portion back to esp_clk_apb_freq() from esp_private/esp_clk.h, which is the approach introduced in #13904. Sorry @swoboda1337 — I shouldn't have pushed back on the private API usage in #13908. It turns out esp_clk_apb_freq() is what the ESP-IDF PCNT driver itself uses internally for glitch filter calculation (pulse_cnt.c:404), it works correctly on all ESP32 variants, and there's simply no public API equivalent. It's what we're stuck with until Espressif provides one.

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Developer breaking change (an API change that could break external components)
• Code quality improvements to existing code or addition of tests
• Other

Related issue or feature (if applicable):

• fixes Compile error with pulse_counter #14069

Pull request in esphome-docs with documentation (if applicable):

• N/A

Test Environment

• ESP32
• ESP32 IDF
• ESP8266
• RP2040
• BK72xx
• RTL87xx
• LN882x
• nRF52840

Example entry for config.yaml:

sensor:
  - platform: pulse_counter
    pin: GPIO18
    name: "Pulse Counter"

Checklist:

• The code change is tested and works locally.
• Tests have been added to verify that the new code works (under tests/ folder).

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated in esphome-docs.