stm32mp1: remove copro_state environment variable

Since the coprocessor state is tracked in a backup register, there is
no more need for tracking it in an environment variable : remove it.

Signed-off-by: Fabien Dessenne <fabien.dessenne@st.com>
Acked-by: Patrick Delaunay <patrick.delaunay@st.com>
diff --git a/board/st/stm32mp1/stm32mp1.c b/board/st/stm32mp1/stm32mp1.c
index cee3500..1d4a54c 100644
--- a/board/st/stm32mp1/stm32mp1.c
+++ b/board/st/stm32mp1/stm32mp1.c
@@ -1096,10 +1096,8 @@
 	printf("Load Remote Processor %d with data@addr=0x%08lx %u bytes:%s\n",
 	       id, fw_image, fw_size, ret ? " Failed!" : " Success!");
 
-	if (!ret) {
+	if (!ret)
 		rproc_start(id);
-		env_set("copro_state", "booted");
-	}
 }
 
 U_BOOT_FIT_LOADABLE_HANDLER(IH_TYPE_COPRO, board_copro_image_process);