ARM: 9128/1: mm: Refactor the __do_page_fault()

Clean up the multiple goto statements and drops local variable
vm_fault_t fault, which will make the __do_page_fault() much more
readability.

No functional change.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>