usb: gadget: remove useless cast

Remove the cast done by ERR_PTR() and PTR_ERR() since data is of type char
* and fss_prepare_buffer() should returns a value of this type.
Acked-by: NFelipe Balbi <balbi@kernel.org>
Signed-off-by: NSalah Triki <salah.triki@gmail.com>
Link: https://lore.kernel.org/r/20210731171838.GA912463@pcSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/function/f_fs.c

@@ -3831,7 +3831,7 @@ static char *ffs_prepare_buffer(const char __user *buf, size_t len)
 
 	data = memdup_user(buf, len);
 	if (IS_ERR(data))
-		return ERR_PTR(PTR_ERR(data));
+		return data;
 
 	pr_vdebug("Buffer from user space:\n");
 	ffs_dump_mem("", data, len);