imx9: use i.MX generic rom api function

There is no need to save gd with using the generic rom api function, so
simplify code.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/arch/arm/mach-imx/imx9/soc.c b/arch/arm/mach-imx/imx9/soc.c
index 07d1bb2..6ae7e70 100644
--- a/arch/arm/mach-imx/imx9/soc.c
+++ b/arch/arm/mach-imx/imx9/soc.c
@@ -49,15 +49,12 @@
 
 int mmc_get_env_dev(void)
 {
-	volatile gd_t *pgd = gd;
 	int ret;
 	u32 boot;
 	u16 boot_type;
 	u8 boot_instance;
 
-	ret = g_rom_api->query_boot_infor(QUERY_BT_DEV, &boot,
-					  ((uintptr_t)&boot) ^ QUERY_BT_DEV);
-	set_gd(pgd);
+	ret = rom_api_query_boot_infor(QUERY_BT_DEV, &boot);
 
 	if (ret != ROM_API_OKAY) {
 		puts("ROMAPI: failure at query_boot_info\n");