serial: ucc_uart: limit brg-frequency workaround to PPC32
According to Timur Tabi
This bug in older U-Boots is definitely PowerPC-specific
So before allowing this driver to be built for platforms other than
PPC32, make sure that we don't accept malformed device trees on those
other platforms.
Suggested-by: Timur Tabi <timur@kernel.org>
Reviewed-by: Timur Tabi <timur@kernel.org>
Acked-by: Timur Tabi <timur@kernel.org>
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Li Yang <leoyang.li@nxp.com>