scsi: ufs: Add counter for hibernate and gear switch

This change adds few more debugfs entries to capture
statistics regarding the ufs driver.
This information include:
1. ufs hibernate exit count
2. ufs power mode change count
usage : cat /sys/kernel/debug/ufshcd0/show_hba

Change-Id: I75ac694c1f7e98d527392372300d16ad911ac512
Signed-off-by: Sayali Lokhande <sayalil@codeaurora.org>