MAINTAINERS: Changing maintainer for ufs DWC.

I am going to leave Synopsys and so this patch changes the Maintainer
for UFS Synopsys' specific drivers to my colleagues Manjunath and Prabu.

Signed-off-by: Joao Pinto <jpinto@synopsys.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>