soc/intel/quark: Add bootblock_c_entry

Add the bootblock_c_entry routine to make it more explicit where the
code transitions from assembler to C.

TEST=Build and run on Galileo Gen2

Change-Id: Ib5f580c30b58d3c82fedddf63c368e617d401515
Signed-off-by: Lee Leahy <leroy.p.leahy@intel.com>
Reviewed-on: https://review.coreboot.org/16064
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>

src/soc/intel/quark/bootblock/bootblock.c

@@ -75,6 +75,11 @@ static const struct reg_script mtrr_init[] = {
 	REG_SCRIPT_END
 };
 
+void asmlinkage bootblock_c_entry(uint64_t base_timestamp)
+{
+	bootblock_main_with_timestamp(base_timestamp);
+}
+
 void bootblock_soc_early_init(void)
 {
 	/* Initialize the MTRRs */

src/soc/intel/quark/bootblock/esram_init.S

@@ -534,6 +534,6 @@ before_carstage:
 	push	%ebp
 
 	/* We can call into C functions now */
-	call bootblock_main_with_timestamp
+	call bootblock_c_entry
 
 	/* Never reached */