MIPS: Lantiq: fix missing xbar kernel panic

Commit 08b3c894 ("MIPS: lantiq: Disable xbar fpi burst mode")
accidentally requested the resources from the pmu address region
instead of the xbar registers region, but the check for the return
value of request_mem_region() was wrong. Commit 98ea51cb ("MIPS:
Lantiq: Fix another request_mem_region() return code check") fixed the
check of the return value of request_mem_region() which made the kernel
panics.
This patch now makes use of the correct memory region for the cross bar.

Fixes: 08b3c894 ("MIPS: lantiq: Disable xbar fpi burst mode")
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Cc: John Crispin <john@phrozen.org>
Cc: james.hogan@imgtec.com
Cc: arnd@arndb.de
Cc: sergei.shtylyov@cogentembedded.com
Cc: john@phrozen.org
Cc: <stable@vger.kernel.org> # 4.4.x-
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/15751


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>