arm: omap: Unify get_device_type() function

Refactor OMAP3/4/5 code so that we have only one get_device_type()
function for all platforms.

Details:
 - Add ctrl variable for AM33xx and OMAP3 platforms (like it's done for
   OMAP4/5), so we can obtain status register in common way
 - For now ctrl structure for AM33xx/OMAP3 contains only status register
   address
 - Run hw_data_init() in order to assign ctrl to proper structure
 - Remove DEVICE_MASK and DEVICE_GP definitions as they are not used
   (DEVICE_TYPE_MASK and GP_DEVICE are used instead)
 - Guard structs in omap_common.h with #ifdefs, because otherwise
   including omap_common.h on non-omap4/5 board files breaks compilation

Buildman script was run for all OMAP boards. Result output:
    arm: (for 38/616 boards)
        all +352.5
        bss -1.4
        data +3.5
        rodata +300.0
        spl/u-boot-spl:all +284.7
        spl/u-boot-spl:data +2.2
        spl/u-boot-spl:rodata +252.0
        spl/u-boot-spl:text +30.5
        text +50.4
    (no errors to report)

Tested on AM57x EVM and BeagleBoard xM.

Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Reviewed-by: Lokesh Vutla <lokeshvutla@ti.com>
[trini: Rework the guards as to not break TI81xx]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/arm/mach-omap2/omap3/board.c b/arch/arm/mach-omap2/omap3/board.c
index 01df579..cd8e302 100644
--- a/arch/arm/mach-omap2/omap3/board.c
+++ b/arch/arm/mach-omap2/omap3/board.c
@@ -173,6 +173,11 @@
 	return;
 }
 
+void early_system_init(void)
+{
+	hw_data_init();
+}
+
 /******************************************************************************
  * Routine: s_init
  * Description: Does early system init of muxing and clocks.
@@ -181,6 +186,7 @@
 void s_init(void)
 {
 	watchdog_init();
+	early_system_init();
 
 	try_unlock_memory();
 
@@ -204,6 +210,7 @@
 #ifdef CONFIG_SPL_BUILD
 void board_init_f(ulong dummy)
 {
+	early_system_init();
 	mem_init();
 }
 #endif