ARM: Fix build regression on SA11x0, PXA, and H720x targets

Build errors similar this appeared in todays kautobuild for the above
targets:

In file included from arch/arm/include/asm/pgtable.h:461,
                 from arch/arm/mach-pxa/generic.c:26:
include/asm-generic/pgtable.h: In function 'ptep_test_and_clear_young':
include/asm-generic/pgtable.h:29: error: dereferencing pointer to incomplete type

None of the .c files including asm/pgtable.h with this error is using
this header, so simply remove the include.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mach-h720x/h7201-eval.c

@@ -23,7 +23,6 @@
 #include <asm/types.h>
 #include <asm/mach-types.h>
 #include <asm/page.h>
-#include <asm/pgtable.h>
 #include <asm/mach/arch.h>
 #include <mach/hardware.h>
 #include "common.h"

arch/arm/mach-h720x/h7202-eval.c

@@ -23,7 +23,6 @@
 #include <asm/types.h>
 #include <asm/mach-types.h>
 #include <asm/page.h>
-#include <asm/pgtable.h>
 #include <asm/mach/arch.h>
 #include <mach/irqs.h>
 #include <mach/hardware.h>

arch/arm/mach-pxa/generic.c

@@ -22,7 +22,6 @@
 
 #include <mach/hardware.h>
 #include <asm/system.h>
-#include <asm/pgtable.h>
 #include <asm/mach/map.h>
 #include <asm/mach-types.h>
 

arch/arm/mach-sa1100/generic.c

@@ -21,7 +21,6 @@
 #include <asm/div64.h>
 #include <mach/hardware.h>
 #include <asm/system.h>
-#include <asm/pgtable.h>
 #include <asm/mach/map.h>
 #include <asm/mach/flash.h>
 #include <asm/irq.h>