scsi: ufs-qti: Check for valid vcc before accessing

This patch fixes a NULL pointer dereference by checking
if vccq & vccq2 are valid before dereferencing it.

Change-Id: Ieb5aefab77428adbbbbf892f2be1a9942d7c3851
Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>