mmc: host: Fix build errors in cqhci-crypto.h

The commit, <65ec3786> (mmc: host: Fix bootup issue with file
encryption with GKI) introduced build error- multiple definitions of
the same function'. Hence, make the stub definitions 'static inline'
to handle the errors.

Change-Id: I42fcc8e47d829fbfd545fe66673a637a2d71b861
Signed-off-by: Raghavendra Rao Ananta <rananta@codeaurora.org>