block: Add SPL_BLOCK_CACHE and default n

When enabling BLOCK_CACHE on devices with limited RAM during SPL,
some devices may not boot.  This creates an option to enable
block caching in SPL by defaults off.  It is dependent on SPL_BLK

Fixes: 46960ad6d09b ("block: Have BLOCK_CACHE default to y in some cases")

Signed-off-by: Adam Ford <aford173@gmail.com>
3 files changed