arm: rmobile: Use imply for BOARD_EARLY_INIT_F

Use "imply" instead of "select" for BOARD_EARLY_INIT_F config option,
and then disable it on boards which don't need it.

Updated grpeach_defconfig to disable CONFIG_BOARD_EARLY_INIT_F option for
RZA1.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 6a02278..abbc89a 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -943,9 +943,9 @@
 
 config ARCH_RMOBILE
 	bool "Renesas ARM SoCs"
-	select BOARD_EARLY_INIT_F if !RZA1
 	select DM
 	select DM_SERIAL
+	imply BOARD_EARLY_INIT_F
 	imply CMD_DM
 	imply FAT_WRITE
 	imply SYS_THUMB_BUILD