HAL_ChibiOS: raise SDMMC clock limit on H7

[tridge]

this allows for faster log download on ethernet.
On CubeRedPrimary log download using the web server on ethernet goes up from 2.4MByte/s to 4.0MByte/s

I don't think this should go straight into 4.5.x, I'd like to see if anyone notices any reliability issues with the faster clock first

[magicrub]

I have a feeling we'll need a way to slow it down if we detect write errors.

[tridge]

I have a feeling we'll need a way to slow it down if we detect write errors.

we do have the parameter BRD_SD_SLOWDOWN already

[rmackay9]

This has led to the JFB110 board becoming unresponsive and even setting BRD_SD_SLOWDOWN to 10 doesn't seem to help

[Copilot]

Pull Request Overview

This PR raises the SDMMC clock limit on the H7 board from 12.5MHz to 50MHz to enable faster log downloads via ethernet. Key changes include:

• Updating the SDMMC clock maximum setting in the hardware configuration header.
• Removing the older reliability comment in favor of the higher clock speed setting.

Comments suppressed due to low confidence (1)

libraries/AP_HAL_ChibiOS/hwdef/common/stm32h7_mcuconf.h:636

• [nitpick] Consider adding a brief note on the reliability tests conducted or recommended precautions for the increased 50MHz clock rate, since the previous comment mentioning reliability has been removed.

// limit SDMMC clock to 50MHz by default