clk: imx8mp: Add i.MX8MP Dummy clk

i.MX8MP SDHC use CLK_IMX8MP_DUMMY clk entry. Without the clk, the bulk
api will return failure.

The correct entry should be replaced with IMX8MP_IPG_ROOT clk in device
tree. This will be done in Kernel device tree and sync to U-Boot in
future:
https://lore.kernel.org/all/20241012025221.1728438-1-peng.fan@oss.nxp.com/



Fixes: 76332fae ("mmc: fsl_esdhc_imx: Enable AHB/IPG clk with clk bulk API")
Reported-by: Gilles Talis <gilles.talis@nxp.com>
Tested-by: Gilles TALIS <gilles.talis@gmail.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>

drivers/clk/imx/clk-imx8mp.c

@@ -197,6 +197,8 @@ static int imx8mp_clk_probe(struct udevice *dev)
 
 	base = (void *)ANATOP_BASE_ADDR;
 
+	clk_dm(IMX8MP_CLK_DUMMY, clk_register_fixed_rate(NULL, "dummy", 0));
+
 	clk_dm(IMX8MP_DRAM_PLL_REF_SEL, imx_clk_mux("dram_pll_ref_sel", base + 0x50, 0, 2, pll_ref_sels, ARRAY_SIZE(pll_ref_sels)));
 	clk_dm(IMX8MP_ARM_PLL_REF_SEL, imx_clk_mux("arm_pll_ref_sel", base + 0x84, 0, 2, pll_ref_sels, ARRAY_SIZE(pll_ref_sels)));
 	clk_dm(IMX8MP_SYS_PLL1_REF_SEL, imx_clk_mux("sys_pll1_ref_sel", base + 0x94, 0, 2, pll_ref_sels, ARRAY_SIZE(pll_ref_sels)));