ARM: dts: Add twl keypad map for LDP

Looks like we're still missing the keypad map for LDP.
Let's add it since we have the binding now available
for the twl4030_keypad as otherwise we get the following
errors during the boot:

twl4030_keypad keypad.31: OF: linux,keymap property not defined
in /ocp/i2c@48070000/twl@48/keypad
twl4030_keypad keypad.31: Failed to build keymap
twl4030_keypad: probe of keypad.31 failed with error -2
Reported-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/boot/dts/omap3-ldp.dts

@@ -7,6 +7,7 @@
  */
 /dts-v1/;
 
+#include <dt-bindings/input/input.h>
 #include "omap34xx.dtsi"
 #include "omap-gpmc-smsc911x.dtsi"
 
@@ -263,6 +264,26 @@ OMAP3_CORE1_IOPAD(0x214e, PIN_INPUT_PULLUP | MUX_MODE0)	/* mmc1_dat3.mmc1_dat3 *
 	};
 };
 
+&twl_keypad {
+	linux,keymap = <MATRIX_KEY(0, 0, KEY_1)
+			MATRIX_KEY(0, 1, KEY_2)
+			MATRIX_KEY(0, 2, KEY_3)
+			MATRIX_KEY(1, 0, KEY_4)
+			MATRIX_KEY(1, 1, KEY_5)
+			MATRIX_KEY(1, 2, KEY_6)
+			MATRIX_KEY(1, 3, KEY_F5)
+			MATRIX_KEY(2, 0, KEY_7)
+			MATRIX_KEY(2, 1, KEY_8)
+			MATRIX_KEY(2, 2, KEY_9)
+			MATRIX_KEY(2, 3, KEY_F6)
+			MATRIX_KEY(3, 0, KEY_F7)
+			MATRIX_KEY(3, 1, KEY_0)
+			MATRIX_KEY(3, 2, KEY_F8)
+			MATRIX_KEY(5, 4, KEY_RESERVED)
+			MATRIX_KEY(4, 4, KEY_VOLUMEUP)
+			MATRIX_KEY(5, 5, KEY_VOLUMEDOWN)>;
+};
+
 &uart3 {
 	interrupts-extended = <&intc 74 &omap3_pmx_core OMAP3_UART3_RX>;
 };