i386: fix PGE mask

cr4 is a 32-bit register, so casting the mask to an unsigned char is wrong,
as it clears more than the PGE bit.
Signed-off-by: Brian Gerst <bgerst@didntduck.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/i386/kernel/cpu/mtrr/cyrix.c

@@ -136,7 +136,7 @@ static void prepare_set(void)
 	/*  Save value of CR4 and clear Page Global Enable (bit 7)  */
 	if ( cpu_has_pge ) {
 		cr4 = read_cr4();
-		write_cr4(cr4 & (unsigned char) ~(1 << 7));
+		write_cr4(cr4 & ~X86_CR4_PGE);
 	}
 
 	/*  Disable and flush caches. Note that wbinvd flushes the TLBs as

arch/i386/kernel/cpu/mtrr/state.c

@@ -19,7 +19,7 @@ void set_mtrr_prepare_save(struct set_mtrr_context *ctxt)
 		/*  Save value of CR4 and clear Page Global Enable (bit 7)  */
 		if ( cpu_has_pge ) {
 			ctxt->cr4val = read_cr4();
-			write_cr4(ctxt->cr4val & (unsigned char) ~(1 << 7));
+			write_cr4(ctxt->cr4val & ~X86_CR4_PGE);
 		}
 
 		/*  Disable and flush caches. Note that wbinvd flushes the TLBs as