hexagon: vm_fault: mark do_page_fault() as static

hexagon: vm_fault: mark do_page_fault() as static

Clang warns:

  arch/hexagon/mm/vm_fault.c:36:6: warning: no previous prototype for function 'do_page_fault' [-Wmissing-prototypes]
     36 | void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)
        |      ^
  arch/hexagon/mm/vm_fault.c:36:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
     36 | void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)
        | ^
        | static

This function is not used outside of this translation unit, so mark it
as static.

Link: https://lkml.kernel.org/r/20231130-hexagon-missing-prototypes-v1-5-5c34714afe9e@kernel.org
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Brian Cain <bcain@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>