[media] am437x-vpfe: always assign bpp variable

In vpfe_s_fmt(), when the sensor format and the requested format were
the same, bpp was assigned to vpfe->bpp without being initialized first.

Grab the bpp value that is currently used by using __vpfe_get_format()
instead of its wrapper, vpfe_try_fmt().

This use of uninitialized variable has been found by compiling the
kernel with clang.

Fixes: 417d2e507edc ("[media] media: platform: add VPFE capture driver
support for AM437X")

Cc: stable@vger.kernel.org
Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/platform/am437x/am437x-vpfe.c

@@ -1576,7 +1576,7 @@ static int vpfe_s_fmt(struct file *file, void *priv,
 		return -EBUSY;
 	}
 
-	ret = vpfe_try_fmt(file, priv, &format);
+	ret = __vpfe_get_format(vpfe, &format, &bpp);
 	if (ret)
 		return ret;