ARM: configs: keystone_defconfig: Enable few peripheral drivers

Enable drivers for QSPI, LEDS, gpio-decoder that are present on 66AK2G EVM
and 66AK2G ICE boards.

Signed-off-by: Vignesh R <vigneshr@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>