configs: at91: Remove CONFIG_SYS_EXTRA_OPTIONS assignment

To remove the assignment of CONFIG_SYS_EXTRA_OPTIONS option,
which is deprecated, use the CONFIG_XXXX_BOOT options to
indicate the boot media, and the SoC is selected by the board.

Signed-off-by: Wenyou Yang <wenyou.yang@microchip.com>
diff --git a/configs/ma5d4evk_defconfig b/configs/ma5d4evk_defconfig
index 0d8c109..cbe76b6 100644
--- a/configs/ma5d4evk_defconfig
+++ b/configs/ma5d4evk_defconfig
@@ -8,7 +8,7 @@
 CONFIG_SPL_SPI_FLASH_SUPPORT=y
 CONFIG_SPL_SPI_SUPPORT=y
 CONFIG_FIT=y
-CONFIG_SYS_EXTRA_OPTIONS="SAMA5D4"
+CONFIG_SYS_EXTRA_OPTIONS=""
 CONFIG_BOOTDELAY=3
 CONFIG_USE_BOOTARGS=y
 CONFIG_BOOTARGS="console=ttyS3,115200"