hugetlb: introduce generic version of hugetlb_free_pgd_range

hugetlb: introduce generic version of hugetlb_free_pgd_range

arm, arm64, mips, parisc, sh, x86 architectures use the same version of
hugetlb_free_pgd_range, so move this generic implementation into
asm-generic/hugetlb.h.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Alexandre Ghiti <[email protected]>
Reviewed-by: Luiz Capitulino <[email protected]>
Reviewed-by: Mike Kravetz <[email protected]>
Tested-by: Helge Deller <[email protected]>			[parisc]
Acked-by: Catalin Marinas <[email protected]>	[arm64]
Acked-by: Paul Burton <[email protected]>		[MIPS]
Acked-by: Ingo Molnar <[email protected]>		[x86]
Cc: Arnd Bergmann <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: David S. Miller <[email protected]>
Cc: Fenghua Yu <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: James E.J. Bottomley <[email protected]>
Cc: James Hogan <[email protected]>
Cc: Martin Schwidefsky <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Ralf Baechle <[email protected]>
Cc: Rich Felker <[email protected]>
Cc: Russell King <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Tony Luck <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Yoshinori Sato <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>