parisc: expose number of page table levels on Kconfig level

We would want to use number of page table level to define mm_struct.
Let's expose it as CONFIG_PGTABLE_LEVELS.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/parisc/kernel/head.S

@@ -74,7 +74,7 @@ $bss_loop:
 	mtctl		%r4,%cr24	/* Initialize kernel root pointer */
 	mtctl		%r4,%cr25	/* Initialize user root pointer */
 
-#if PT_NLEVELS == 3
+#if CONFIG_PGTABLE_LEVELS == 3
 	/* Set pmd in pgd */
 	load32		PA(pmd0),%r5
 	shrd            %r5,PxD_VALUE_SHIFT,%r3	
@@ -97,7 +97,7 @@ $bss_loop:
 	stw		%r3,0(%r4)
 	ldo		(PAGE_SIZE >> PxD_VALUE_SHIFT)(%r3),%r3
 	addib,>		-1,%r1,1b
-#if PT_NLEVELS == 3
+#if CONFIG_PGTABLE_LEVELS == 3
 	ldo             ASM_PMD_ENTRY_SIZE(%r4),%r4
 #else
 	ldo             ASM_PGD_ENTRY_SIZE(%r4),%r4