omap-common: Common omap_die_id definition

This introduces a common definition for omap_die_id, that aims at providing a
common interface for accessing omap platform's die id bits.

Signed-off-by: Paul Kocialkowski <contact@paulk.fr>
Reviewed-by: Tom Rini <trini@konsulko.com>

arch/arm/cpu/armv7/omap-common/utils.c

@@ -41,6 +41,11 @@ void cancel_out(u32 *num, u32 *den, u32 den_limit)
 	}
 }
 
+__weak void omap_die_id(unsigned int *die_id)
+{
+	die_id[0] = die_id[1] = die_id[2] = die_id[3] = 0;
+}
+
 void __weak usb_fake_mac_from_die_id(u32 *id)
 {
 	uint8_t device_mac[6];

arch/arm/include/asm/omap_common.h

@@ -612,6 +612,8 @@ void omap_smc1(u32 service, u32 val);
 void enable_edma3_clocks(void);
 void disable_edma3_clocks(void);
 
+void omap_die_id(unsigned int *die_id);
+
 /* ABB */
 #define OMAP_ABB_NOMINAL_OPP		0
 #define OMAP_ABB_FAST_OPP		1