configs: am335x_guardian: add register maps support

add support to direct memory access of hardware peripherals registers

Signed-off-by: Gireesh Hiremath <Gireesh.Hiremath@in.bosch.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Link: https://lore.kernel.org/r/20210611161350.2141-19-Gireesh.Hiremath@in.bosch.com

configs/am335x_guardian_defconfig

@@ -72,6 +72,7 @@ CONFIG_SPL_ENV_IS_NOWHERE=y
 CONFIG_VERSION_VARIABLE=y
 CONFIG_BOOTP_SEND_HOSTNAME=y
 CONFIG_SPL_DM=y
+CONFIG_REGMAP=y
 CONFIG_BOOTCOUNT_LIMIT=y
 CONFIG_BOOTCOUNT_AM33XX_NVMEM=y
 CONFIG_CLK=y