ARM: pxa: moved pxa27x_keypad.h to platform pxa directory

mach-mmp utilizes pxa27x_keypad code so we need to move header to
platform pxa directory.

Signed-off-by: Mark F. Brown <mark.brown314@gmail.com>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>
diff --git a/arch/arm/mach-pxa/z2.c b/arch/arm/mach-pxa/z2.c
index f0d0228..8c44bc4 100644
--- a/arch/arm/mach-pxa/z2.c
+++ b/arch/arm/mach-pxa/z2.c
@@ -37,7 +37,7 @@
 #include <mach/z2.h>
 #include <mach/pxafb.h>
 #include <mach/mmc.h>
-#include <mach/pxa27x_keypad.h>
+#include <plat/pxa27x_keypad.h>
 #include <mach/pxa2xx_spi.h>
 
 #include <plat/i2c.h>