UPSTREAM: scsi: ufs: ufs-mediatek: Fix error checking in ufs_mtk_init_va09_pwr_ctrl()

The function regulator_get() returns an error pointer. Use IS_ERR() to
validate the return value.

Bug: 254441685
Link: https://lore.kernel.org/r/20211222070930.9449-1-linmq006@gmail.com


Fixes: cf137b3e ("scsi: ufs-mediatek: Support VA09 regulator operations")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
(cherry picked from commit 3ba880a1)
Signed-off-by: Lee Jones <joneslee@google.com>
Change-Id: Iccf8b09bb8f837139cb4bc7bfc21b29d3423d5b9