ARM: defconfig: lpc32xx: enable generic SRAM driver

NXP LPC32xx SoCs contain an IRAM area, which is supported by
the generic MMIO SRAM driver, enable the driver to be built
by default.
Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>

arch/arm/configs/lpc32xx_defconfig

@@ -56,6 +56,7 @@ CONFIG_BLK_DEV_CRYPTOLOOP=y
 CONFIG_BLK_DEV_RAM=y
 CONFIG_BLK_DEV_RAM_COUNT=1
 CONFIG_BLK_DEV_RAM_SIZE=16384
+CONFIG_SRAM=y
 CONFIG_EEPROM_AT24=y
 CONFIG_EEPROM_AT25=y
 CONFIG_SCSI=y