x86/mem_access: move p2m_mem_access_sanity_check() from header

x86/mem_access: move p2m_mem_access_sanity_check() from header

Move p2m_mem_access_sanity_check() from the asm-x86/mem_access.h
header, where it currently is declared inline, to
arch/x86/mm/mem_access.c. This allows source code that includes it
directly, or indirectly (such as xen/mem_access.h), to not worry
about also including sched.h for is_hvm_domain(). Including
xen/mem_access.h is useful for code wanting to use p2m_access_t.

Signed-off-by: Razvan Cojocaru <rcojocaru@bitdefender.com>
Acked-by: Tamas K Lengyel <tamas@tklengyel.com>