am437x: Add am437x_gp_evm_defconfig using CONFIG_DM

Import various DT files for am4372, an43xx pinctrl and
am437x-gp-evm from Linux Kernel v4.2
Add config file for this board, enable DM, DM_GPIO, DM_SERIAL
and DM_MMC.

Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Reviewed-by: Lokesh Vutla <lokeshvutla@ti.com>
diff --git a/include/dt-bindings/pwm/pwm.h b/include/dt-bindings/pwm/pwm.h
new file mode 100644
index 0000000..96f49e8
--- /dev/null
+++ b/include/dt-bindings/pwm/pwm.h
@@ -0,0 +1,14 @@
+/*
+ * This header provides constants for most PWM bindings.
+ *
+ * Most PWM bindings can include a flags cell as part of the PWM specifier.
+ * In most cases, the format of the flags cell uses the standard values
+ * defined in this header.
+ */
+
+#ifndef _DT_BINDINGS_PWM_PWM_H
+#define _DT_BINDINGS_PWM_PWM_H
+
+#define PWM_POLARITY_INVERTED			(1 << 0)
+
+#endif