MIPS: generic: Fix machine compatible matching

MIPS: generic: Fix machine compatible matching

BugLink: http://bugs.launchpad.net/bugs/1786352
[ Upstream commit 9a9ab3078e2744a1a55163cfaec73a5798aae33e ]

We now have a platform (Ranchu) in the "generic" platform which matches
based on the FDT compatible string using mips_machine_is_compatible(),
however that function doesn't stop at a blank struct
of_device_id::compatible as that is an array in the struct, not a
pointer to a string.

Fix the loop completion to check the first byte of the compatible array
rather than the address of the compatible array in the struct.

Fixes: eed0eabd12ef ("MIPS: generic: Introduce generic DT-based board support")
Signed-off-by: James Hogan <jhogan@kernel.org>
Reviewed-by: Paul Burton <paul.burton@mips.com>
Reviewed-by: Matt Redfearn <matt.redfearn@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/18580/
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>