armv8: QSPI: Add AHB bus 16MB+ size support

The default configuration for QSPI AHB bus can't support 16MB+.
But some flash on NXP layerscape board are more than 16MB.

Signed-off-by: Yuan Yao <yao.yuan@nxp.com>
Reviewed-by: York Sun <york.sun@nxp.com>
8 files changed