MIPS: ip22: Fix ip28 build for modern gcc

MIPS: ip22: Fix ip28 build for modern gcc

kernelci reports a failure of the ip28_defconfig build after upgrading its
gcc version:

arch/mips/sgi-ip22/Platform:29: *** gcc doesn't support needed option -mr10k-cache-barrier=store.  Stop.

The problem apparently is that the -mr10k-cache-barrier=store option is now
rejected for CPUs other than r10k. Explicitly including the CPU in the
check fixes this and is safe because both options were introduced in
gcc-4.4.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/15049/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>