clk: imx8mm: add SNVS clock to clock tree

i.MX8MM has clock gate for SNVS module, add it into clock tree
for SNVS RTC driver to manage.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Reviewed-by: Leonard Crestez <leonard.crestez@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

drivers/clk/imx/clk-imx8mm.c

@@ -622,6 +622,7 @@ static int __init imx8mm_clocks_init(struct device_node *ccm_node)
 	clks[IMX8MM_CLK_SAI5_IPG] = imx_clk_gate2_shared2("sai5_ipg_clk", "ipg_audio_root", base + 0x4370, 0, &share_count_sai5);
 	clks[IMX8MM_CLK_SAI6_ROOT] = imx_clk_gate2_shared2("sai6_root_clk", "sai6", base + 0x4380, 0, &share_count_sai6);
 	clks[IMX8MM_CLK_SAI6_IPG] = imx_clk_gate2_shared2("sai6_ipg_clk", "ipg_audio_root", base + 0x4380, 0, &share_count_sai6);
+	clks[IMX8MM_CLK_SNVS_ROOT] = imx_clk_gate4("snvs_root_clk", "ipg_root", base + 0x4470, 0);
 	clks[IMX8MM_CLK_UART1_ROOT] = imx_clk_gate4("uart1_root_clk", "uart1", base + 0x4490, 0);
 	clks[IMX8MM_CLK_UART2_ROOT] = imx_clk_gate4("uart2_root_clk", "uart2", base + 0x44a0, 0);
 	clks[IMX8MM_CLK_UART3_ROOT] = imx_clk_gate4("uart3_root_clk", "uart3", base + 0x44b0, 0);