boards: silabs: siwx91x: Fix MEMC enable and initialization priorities

This commit corrects board configuration to enable the memory controller
and set proper initialization priorities, ensuring PSRAM is correctly
initialized during system startup.

Signed-off-by: S Mohamed Fiaz <[email protected]>

Author: fimohame

boards/silabs/dev_kits/siwx917_dk2605a/siwx917_dk2605a_defconfig

@@ -7,3 +7,7 @@ CONFIG_CONSOLE=y
 CONFIG_UART_CONSOLE=y
 CONFIG_SERIAL=y
 CONFIG_CLOCK_CONTROL=y
+CONFIG_MEMC=y
+
+CONFIG_CLOCK_CONTROL_INIT_PRIORITY=28
+CONFIG_MEMC_INIT_PRIORITY=29