cputlb: Partially inline memory_region_section_get_iotlb

cputlb: Partially inline memory_region_section_get_iotlb

There is only one caller, tlb_set_page_with_attrs.  We cannot
inline the entire function because the AddressSpaceDispatch
structure is private to exec.c, and cannot easily be moved to
include/exec/memory-internal.h.

Compute is_ram and is_romd once within tlb_set_page_with_attrs.
Fold the number of tests against these predicates.  Compute
cpu_physical_memory_is_clean outside of the tlb lock region.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>