fix(sdmmc): Fix missing initializer warnings

Author: P-R-O-C-H-Y

libraries/SD_MMC/src/SD_MMC.cpp

@@ -228,7 +228,17 @@ bool SDMMCFS::begin(const char *mountpoint, bool mode1bit, bool format_if_mount_
 #if defined(CONFIG_IDF_TARGET_ESP32P4) && defined(BOARD_SDMMC_SLOT) && (BOARD_SDMMC_SLOT == 0)
   host.slot = SDMMC_HOST_SLOT_0;
   // reconfigure slot_config to remove all pins in order to use IO_MUX
-  slot_config = {
+  slot_config = sdmmc_slot_config_t{
+    .clk = GPIO_NUM_NC,
+    .cmd = GPIO_NUM_NC,
+    .d0 = GPIO_NUM_NC,
+    .d1 = GPIO_NUM_NC,
+    .d2 = GPIO_NUM_NC,
+    .d3 = GPIO_NUM_NC,
+    .d4 = GPIO_NUM_NC,
+    .d5 = GPIO_NUM_NC,
+    .d6 = GPIO_NUM_NC,
+    .d7 = GPIO_NUM_NC,
     .cd = SDMMC_SLOT_NO_CD,
     .wp = SDMMC_SLOT_NO_WP,
     .width = 4,