parisc: use PAGE_SHIFT instead of hardcoded value 12 in pacache.S

additionally clean up some whitespaces & tabs.
Signed-off-by: Helge Deller <deller@gmx.de>

arch/parisc/kernel/pacache.S

@@ -612,7 +612,7 @@ ENTRY(copy_user_page_asm)
 	extrw,u		%r26, 24,25, %r26	/* convert phys addr to tlb insert format */
 	extrw,u		%r23, 24,25, %r23	/* convert phys addr to tlb insert format */
 	depw		%r24, 31,22, %r28	/* Form aliased virtual address 'to' */
-	depwi		0, 31,12, %r28		/* Clear any offset bits */
+	depwi		0, 31,PAGE_SHIFT, %r28	/* Clear any offset bits */
 	copy		%r28, %r29
 	depwi		1, 9,1, %r29		/* Form aliased virtual address 'from' */
 #endif
@@ -762,7 +762,7 @@ ENTRY(clear_user_page_asm)
 #else
 	extrw,u		%r26, 24,25, %r26	/* convert phys addr to tlb insert format */
 	depw		%r25, 31,22, %r28	/* Form aliased virtual address 'to' */
-	depwi		0, 31,12, %r28		/* Clear any offset bits */
+	depwi		0, 31,PAGE_SHIFT, %r28	/* Clear any offset bits */
 #endif
 
 	/* Purge any old translation */
@@ -846,7 +846,7 @@ ENTRY(flush_dcache_page_asm)
 #else
 	extrw,u		%r26, 24,25, %r26	/* convert phys addr to tlb insert format */
 	depw		%r25, 31,22, %r28	/* Form aliased virtual address 'to' */
-	depwi		0, 31,12, %r28		/* Clear any offset bits */
+	depwi		0, 31,PAGE_SHIFT, %r28	/* Clear any offset bits */
 #endif
 
 	/* Purge any old translation */
@@ -922,7 +922,7 @@ ENTRY(flush_icache_page_asm)
 #else
 	extrw,u		%r26, 24,25, %r26	/* convert phys addr to tlb insert format */
 	depw		%r25, 31,22, %r28	/* Form aliased virtual address 'to' */
-	depwi		0, 31,12, %r28		/* Clear any offset bits */
+	depwi		0, 31,PAGE_SHIFT, %r28	/* Clear any offset bits */
 #endif
 
 	/* Purge any old translation */