boardid: Minor clean up and standardization

Merge the different coreboot table strapping ID structures into one
because they're really just all the same, and I want to add more. Make
the signature of the board_id() function return a uint32_t because
that's also what goes in the coreboot table. Add a printk to the generic
code handling strapping IDs in ramstage so that not every individual
mainboard implementation needs its own print. (In turn, remove one such
print from fsp1_1 code because it's in the way of my next patch.)

Change-Id: Ib9563edf07b623a586a4dc168fe357564c5e68b5
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/22741
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/intel/glkrvp/boardid.c

@@ -23,7 +23,7 @@
 #define BOARD_ID_GLK_RVP2_LP4	0x8 /* RVP2 - LP4 Socket */
 #define EC_FAB_ID_CMD	0x0D /* Get the board fab ID in the lower 3 bits */
 
-uint8_t board_id(void)
+uint32_t board_id(void)
 {
 	MAYBE_STATIC int id = -1;
 	if (id < 0) {