west.yml: update modules hal stm32 for stm32mp2x

Update west.yml to add the STM32MP2x SoC support in the STM32 HAL.
This is done after the merge of the PR::
zephyrproject-rtos/hal_stm32#282
It now references the fix pull request of the stm32mp2 HAL:
zephyrproject-rtos/hal_stm32#286

Signed-off-by: Youssef Zini <youssef.zini@savoirfairelinux.com>

Author: youssefz24

west.yml

@@ -245,7 +245,7 @@ manifest:
       groups:
         - hal
     - name: hal_stm32
-      revision: 5cbc642b1a79d4f373b1587f8c3027f31bf0d30c
+      revision: pull/286/head
       path: modules/hal/stm32
       groups:
         - hal