MIPS: IP28: Fix/clean spaces.h

Broken values for UNCAC_BASE/IO_BASE caused complete breakage of IP28
builds. Only set special PHY_OFFSET and take everything else from
generic spaces.h

Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7549/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
(cherry picked from commit 81832d7e7962a40d08d9fe2e7e71b7887bc30097)