soc/intel: Move pmc_soc_set_afterg3_en() to pmutil.c

Commit 2c26108208 moved this function to
pmutil.c for Tiger Lake. Do this to all other platforms for consistency.
For Skylake, __SIMPLE_DEVICE__ preprocessor guards are no longer needed.

With this change, pmc.c is only needed in ramstage. Adjust Makefile.inc
accordingly, and drop ENV_RAMSTAGE guards from Skylake.

Change-Id: I424eb359c898f155659d085b888410b6bb58b9ed
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/52464
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-by: Michael Niewöhner <foss@mniewoehner.de>

src/soc/intel/apollolake/pmutil.c

@@ -224,3 +224,16 @@ uint16_t get_pmbase(void)
 {
 	return (uint16_t) ACPI_BASE_ADDRESS;
 }
+
+void pmc_soc_set_afterg3_en(const bool on)
+{
+	void *const gen_pmcon1 = (void *)(soc_read_pmc_base() + GEN_PMCON1);
+	uint32_t reg32;
+
+	reg32 = read32(gen_pmcon1);
+	if (on)
+		reg32 &= ~SLEEP_AFTER_POWER_FAIL;
+	else
+		reg32 |= SLEEP_AFTER_POWER_FAIL;
+	write32(gen_pmcon1, reg32);
+}