Fix USB host not mounting USB drive sometimes

After an unmountable drive is inserted and ejected, a valid drive won't mount
[no ci]

firmware/src/usb/msc_fatfs_ops.hh

@@ -1,5 +1,6 @@
 #pragma once
 #include "disk_ops.hh"
+#include "usbh_conf.h"
 #include "usbh_def.h"
 #include "usbh_msc.h"
 
@@ -23,7 +24,18 @@ public:
 	}
 
 	DSTATUS initialize() override {
-		return (is_mounted_ && msc_isready()) ? 0 : STA_NODISK | STA_NOINIT;
+		auto ready = msc_isready();
+		if (ready) {
+			if (!is_mounted_)
+				USBH_UsrLog("MSC is ready, mounting\n");
+			is_mounted_ = true;
+		} else
+			USBH_ErrLog("MSC is not ready, cannot initialize\n");
+
+		DSTATUS status = is_mounted_ ? 0 : STA_NODISK;
+		status |= ready ? 0 : STA_NOINIT;
+
+		return status;
 	}
 
 	DRESULT read(uint8_t *dst, uint32_t sector_start, uint32_t num_sectors) override {

firmware/src/usb/msc_host.hh

@@ -28,10 +28,12 @@ public:
 	}
 
 	void connect() {
-		// Do nothing: subsequent fileio operations will call mount_disk()
+		pr_trace("USB MSC connect(): calling mount_disk()\n");
+		msc.mount_disk();
 	}
 
 	void disconnect() {
+		pr_trace("USB MSC disconnect()\n");
 		msc.unmount_disk();
 	}