mmc: core: disable cache for micron eMMC devices

Enabling cache in micron devices with manufacturer ID 0xFE
is resulting in data corruption issues during power-off tests.

CRs-fixed: 654661
Change-Id: Ifcdecb26c4c75b055a128a8d9b883fc028521930
Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>