axs10x/emdk/hsdk/iot_dk: Implement board_mmc_getcd()

So now we may detect MMC/SD-card existence and
instead of completely misleading message on missing card:
------------------------>8-----------------------
Loading Environment from FAT... Card did not respond to voltage select!
------------------------>8-----------------------

we now get very clear one:
------------------------>8-----------------------
Loading Environment from FAT... MMC: no card present
------------------------>8-----------------------

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>

board/synopsys/axs10x/axs10x.c

@@ -33,6 +33,13 @@ int board_mmc_init(bd_t *bis)
 	return 0;
 }
 
+int board_mmc_getcd(struct mmc *mmc)
+{
+	struct dwmci_host *host = mmc->priv;
+
+	return !(dwmci_readl(host, DWMCI_CDETECT) & 1);
+}
+
 #define AXS_MB_CREG	0xE0011000
 
 int board_early_init_f(void)

board/synopsys/emdk/emdk.c

@@ -34,6 +34,13 @@ int board_mmc_init(bd_t *bis)
 	return 0;
 }
 
+int board_mmc_getcd(struct mmc *mmc)
+{
+	struct dwmci_host *host = mmc->priv;
+
+	return !(dwmci_readl(host, DWMCI_CDETECT) & 1);
+}
+
 #define CREG_BASE		0xF0001000
 #define CREG_BOOT_OFFSET	0
 #define CREG_BOOT_WP_OFFSET	8

board/synopsys/hsdk/hsdk.c

@@ -1019,6 +1019,13 @@ int board_late_init(void)
 	return 0;
 }
 
+int board_mmc_getcd(struct mmc *mmc)
+{
+	struct dwmci_host *host = mmc->priv;
+
+	return !(dwmci_readl(host, DWMCI_CDETECT) & 1);
+}
+
 int board_mmc_init(bd_t *bis)
 {
 	struct dwmci_host *host = NULL;

board/synopsys/iot_devkit/iot_devkit.c

@@ -170,6 +170,13 @@ int board_mmc_init(bd_t *bis)
 	return 0;
 }
 
+int board_mmc_getcd(struct mmc *mmc)
+{
+	struct dwmci_host *host = mmc->priv;
+
+	return !(dwmci_readl(host, DWMCI_CDETECT) & 1);
+}
+
 #define IOTDK_RESET_SEQ		0x55AA6699
 
 void reset_cpu(ulong addr)