MIPS: entry: Remove unneeded need_resched() loop

Since the enabling and disabling of IRQs within preempt_schedule_irq()
is contained in a need_resched() loop, we don't need the outer arch
code loop.

Note that commit a18815ab ("Use preempt_schedule_irq.") initially
removed the existing loop, but missed the final branch to restore_all.
Commit cdaed73a ("Fix preemption bug.") missed that and reintroduced
the loop.

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@mips.com>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@vger.kernel.org
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-kernel@vger.kernel.org