soc/fsl/guts: Add compatible string for LS1088

Adding compatible string "ls1088a-dcfg" so that
guts driver can be init for ls1088

Signed-off-by: Ashish Kumar <Ashish.Kumar@nxp.com>
Signed-off-by: Amrita Kumari <amrita.kumari@nxp.com>
Signed-off-by: Li Yang <leoyang.li@nxp.com>