mmc: core: fix issue with sleep cmd that follows an RPMB access

If the last access to eMMC before runtime/system suspend is an
RPMB access, the partition type within EXT_CSD[179] will be set
to RPMB. As per specification, the deselect CMD7 and sleep CMD5
are ignored by the card and are treated as illegal commands in
this state. This causes eMMC sleep command to timeout and thus
fails runtime/system suspend. Hence, switch to default partition
config before sending deselect CMD7 and sleep CMD5.

CRs-fixed: 630894
Change-Id: I40f3fb590aeba787de8ca3356a8eed5f2780bcc1
Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
Signed-off-by: Venkat Gopalakrishnan <venkatg@codeaurora.org>