clk: imx8mn: add SNVS clock to clock tree

i.mx8mn has support for clock gating the snvs module.
Add it into clock tree so that rtc-snvs driver could use it.

Note this will also be required in the snvs_pwrkey driver,
once support for clock management will be added.
Signed-off-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

drivers/clk/imx/clk-imx8mn.c

@@ -523,6 +523,7 @@ static int imx8mn_clocks_probe(struct platform_device *pdev)
 	hws[IMX8MN_CLK_SAI5_IPG] = imx_clk_hw_gate2_shared2("sai5_ipg_clk", "ipg_audio_root", base + 0x4370, 0, &share_count_sai5);
 	hws[IMX8MN_CLK_SAI6_ROOT] = imx_clk_hw_gate2_shared2("sai6_root_clk", "sai6", base + 0x4380, 0, &share_count_sai6);
 	hws[IMX8MN_CLK_SAI6_IPG] = imx_clk_hw_gate2_shared2("sai6_ipg_clk", "ipg_audio_root", base + 0x4380, 0, &share_count_sai6);
+	hws[IMX8MN_CLK_SNVS_ROOT] = imx_clk_hw_gate4("snvs_root_clk", "ipg_root", base + 0x4470, 0);
 	hws[IMX8MN_CLK_UART1_ROOT] = imx_clk_hw_gate4("uart1_root_clk", "uart1", base + 0x4490, 0);
 	hws[IMX8MN_CLK_UART2_ROOT] = imx_clk_hw_gate4("uart2_root_clk", "uart2", base + 0x44a0, 0);
 	hws[IMX8MN_CLK_UART3_ROOT] = imx_clk_hw_gate4("uart3_root_clk", "uart3", base + 0x44b0, 0);