If no voltage supply regulators are defined for the UFS devices (assumed
they are always-on), ufshcd_config_vreg_load() can be called on
suspend/resume paths with vreg == NULL as hba->vreg_info.vcc* equal to
NULL, and it causes NULL pointer dereference.

This fixes it by making ufshcd_config_vreg_{h,l}pm noop when no regulators
are defined.
Signed-off-by: NAkinobu Mita <mita@fixstars.com>
Reviewed-by: NSubhash Jadavani <subhashj@codeaurora.org>
Signed-off-by: NChristoph Hellwig <hch@lst.de>