x86: sandbox: Add a PMC emulator and test

Add a simple PMC for sandbox to permit tests to run.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/drivers/Makefile b/drivers/Makefile
index e977f19..cb8c215 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -25,6 +25,7 @@
 obj-$(CONFIG_$(SPL_)DM_MAILBOX) += mailbox/
 obj-$(CONFIG_$(SPL_)REMOTEPROC) += remoteproc/
 obj-$(CONFIG_$(SPL_TPL_)TPM) += tpm/
+obj-$(CONFIG_$(SPL_TPL_)ACPI_PMC) += power/acpi_pmc/
 
 ifndef CONFIG_TPL_BUILD
 ifdef CONFIG_SPL_BUILD