tcg: Use CPUClass::tlb_fill in cputlb.c

tcg: Use CPUClass::tlb_fill in cputlb.c

We can now use the CPUClass hook instead of a named function.

Create a static tlb_fill function to avoid other changes within
cputlb.c.  This also isolates the asserts within.  Remove the
named tlb_fill function from all of the targets.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>