target-arm: Move setting of exception info into tlb_fill

target-arm: Move setting of exception info into tlb_fill

Move the code which sets exception information out of
arm_cpu_handle_mmu_fault and into tlb_fill. tlb_fill
is the only caller which wants to raise_exception()
so it makes more sense for it to handle the whole of
the exception setup.

As part of this cleanup, move the user-mode-only
implementation function for the handle_mmu_fault CPU
method into cpu.c so we don't need to make it globally
visible, and rename the softmmu-only utility function
arm_cpu_handle_mmu_fault to arm_tlb_fill so it's clear
that it's not the same thing.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>