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/sama5d2_ptc_spiflash_defconfig b/configs/sama5d2_ptc_spiflash_defconfig
index e4fb49f..ad62f47 100644
--- a/configs/sama5d2_ptc_spiflash_defconfig
+++ b/configs/sama5d2_ptc_spiflash_defconfig
@@ -7,7 +7,7 @@
 CONFIG_SPL_SERIAL_SUPPORT=y
 CONFIG_SPL_SPI_FLASH_SUPPORT=y
 CONFIG_SPL_SPI_SUPPORT=y
-CONFIG_SYS_EXTRA_OPTIONS="SAMA5D2,SYS_USE_SERIALFLASH"
+CONFIG_SPI_BOOT=y
 CONFIG_BOOTDELAY=3
 CONFIG_USE_BOOTARGS=y
 CONFIG_BOOTARGS="console=ttyS0,57600 earlyprintk mtdparts=atmel_nand:6M(bootstrap)ro, 6M(kernel)ro,-(rootfs) rootfstype=ubifs ubi.mtd=2 root=ubi0:rootfs"