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/board/atmel/at91sam9n12ek/at91sam9n12ek.c b/board/atmel/at91sam9n12ek/at91sam9n12ek.c
index fec9316..540adf5 100644
--- a/board/atmel/at91sam9n12ek/at91sam9n12ek.c
+++ b/board/atmel/at91sam9n12ek/at91sam9n12ek.c
@@ -224,11 +224,11 @@
 
 void at91_spl_board_init(void)
 {
-#ifdef CONFIG_SYS_USE_MMC
+#ifdef CONFIG_SD_BOOT
 	at91_mci_hw_init();
-#elif CONFIG_SYS_USE_NANDFLASH
+#elif CONFIG_NAND_BOOT
 	at91sam9n12ek_nand_hw_init();
-#elif CONFIG_SYS_USE_SPIFLASH
+#elif CONFIG_SPI_BOOT
 	at91_spi0_hw_init(1 << 4);
 #endif
 }