arm-trusted-firmware-stm32: bump to v2.12

arm-trusted-firmware-stm32: bump to v2.12

No need to pass the option no-warn-rwx-segments. Since v2.12, TF-A
automatically selects it if needed.

A patch is added to revert commit 03a581e2 ("feat(stm32mp1-fdts): remove
RTC clock configuration").
This commit removed RTC clock configuration, as it assumed that it was done
correctly by OPTEE.
But it is not the case. Without this patch the RTC is in a bad state,
consequently the wifi module cannot be initialized.

stm32_rtc 5c004000.rtc: rtc_ck is slow
stm32_rtc 5c004000.rtc: Can't enter in init mode. Prescaler config failed.
stm32_rtc: probe of 5c004000.rtc failed with error -110

sdio mmc1:0001:1: Direct firmware load for brcm/brcmfmac43430-sdio.st,stm32mp135f-dk.bin failed with error -2
brcmfmac: brcmf_sdio_htclk: HT Avail timeout (1000000): clkctl 0x50

Tested on STM32MP135F-DK.

Signed-off-by: Thomas Richard <thomas.richard@bootlin.com>
Link: https://github.com/openwrt/openwrt/pull/17243
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>