am335x-evm: Support STMicro/Micron SPI flash

This change enables access to the SPI flash on the SanCloud BBE Lite
board.

Signed-off-by: Paul Barker <paul.barker@sancloud.com>
diff --git a/configs/am335x_evm_defconfig b/configs/am335x_evm_defconfig
index f0fbe47..f73123e 100644
--- a/configs/am335x_evm_defconfig
+++ b/configs/am335x_evm_defconfig
@@ -92,6 +92,7 @@
 CONFIG_SYS_NAND_U_BOOT_OFFS=0xc0000
 CONFIG_DM_SPI_FLASH=y
 CONFIG_SF_DEFAULT_SPEED=24000000
+CONFIG_SPI_FLASH_STMICRO=y
 CONFIG_SPI_FLASH_WINBOND=y
 CONFIG_PHY_ATHEROS=y
 CONFIG_PHY_SMSC=y