x86/mm: Initialize pmd_idx in page_table_range_init_count()

The variable pmd_idx is not initialized for the first iteration of the
for loop.

Assign the proper value which indexes the start address.

Fixes: 719272c45b 'x86, mm: only call early_ioremap_page_table_range_init() once'
Signed-off-by: Minfei Huang <mnfhuang@gmail.com>
Cc: tony.luck@intel.com
Cc: wangnan0@huawei.com
Cc: david.vrabel@citrix.com
Reviewed-by: yinghai@kernel.org
Link: http://lkml.kernel.org/r/1436703522-29552-1-git-send-email-mhuang@redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/mm/init_32.c

@@ -137,6 +137,7 @@ page_table_range_init_count(unsigned long start, unsigned long end)
 
 	vaddr = start;
 	pgd_idx = pgd_index(vaddr);
+	pmd_idx = pmd_index(vaddr);
 
 	for ( ; (pgd_idx < PTRS_PER_PGD) && (vaddr != end); pgd_idx++) {
 		for (; (pmd_idx < PTRS_PER_PMD) && (vaddr != end);