feat(imx8m): add the PU power domain support on imx8mm/mn

Add the PU power domain support for imx8mm/mn.

Signed-off-by: Jacky Bai <ping.bai@nxp.com>
Change-Id: Ib88b4b5db956fdf2c77d2f2f3723d61a7060409d
diff --git a/plat/imx/imx8m/include/gpc.h b/plat/imx/imx8m/include/gpc.h
index 16129d1..a41030e 100644
--- a/plat/imx/imx8m/include/gpc.h
+++ b/plat/imx/imx8m/include/gpc.h
@@ -70,5 +70,6 @@
 void imx_set_rbc_count(void);
 void imx_clear_rbc_count(void);
 void imx_anamix_override(bool enter);
+void imx_gpc_pm_domain_enable(uint32_t domain_id, bool on);
 
 #endif /*IMX8M_GPC_H */