soc/intel/apollolake: add soc implementation for ETR address API

Add soc implementation for the new ETR address API.

Change-Id: I1832f5f14055fc3dbb502289035130ca7a5d6d33
Signed-off-by: Michael Niewöhner <foss@mniewoehner.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/36566
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/soc/intel/apollolake/pmutil.c

@@ -49,6 +49,11 @@ uintptr_t soc_read_pmc_base(void)
 	return read_pmc_mmio_bar();
 }
 
+uint32_t *soc_pmc_etr_addr(void)
+{
+	return (uint32_t *)(soc_read_pmc_base() + ETR);
+}
+
 const char *const *soc_smi_sts_array(size_t *a)
 {
 	static const char *const smi_sts_bits[] = {