board: phycore-imx93: env: Add prepare_mcore to environment

Add prepare_mcore script to environment to be able to notify Linux about
the state of M33 core via the kernel cmdline by appending to ${optargs}.

Signed-off-by: Primoz Fiser <primoz.fiser@norik.com>
diff --git a/board/phytec/phycore_imx93/phycore_imx93.env b/board/phytec/phycore_imx93/phycore_imx93.env
index 36bf3fe..52c234a 100644
--- a/board/phytec/phycore_imx93/phycore_imx93.env
+++ b/board/phytec/phycore_imx93/phycore_imx93.env
@@ -9,6 +9,7 @@
 bootenv_addr_r=0x90500000
 fdtfile=CONFIG_DEFAULT_FDT_FILE
 ip_dyn=yes
+prepare_mcore=setenv optargs "${optargs} clk-imx93.mcore_booted"
 mmcdev=CONFIG_SYS_MMC_ENV_DEV
 mmcpart=1
 mmcroot=2