MIPS: check return value of pgtable_pmd_page_ctor

MIPS: check return value of pgtable_pmd_page_ctor

[ Upstream commit 6aa32467299e9e12280a6aec9dbc21bf2db830b0 ]

+. According to Documentation/vm/split_page_table_lock, handle failure
of pgtable_pmd_page_ctor

+. Use GFP_KERNEL_ACCOUNT instead of GFP_KERNEL|__GFP_ACCOUNT

+. Adjust coding style

Fixes: ed914d48b6a1 ("MIPS: add PMD table accounting into MIPS')
Reported-by: Joshua Kinard <kumba@gentoo.org>
Signed-off-by: Huang Pei <huangpei@loongson.cn>
Reviewed-by: Joshua Kinard <kumba@gentoo.org>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>