Revert "USB: serial: make bulk_out_size a lower limit"

Revert "USB: serial: make bulk_out_size a lower limit"

commit bc4b1f486fe69b86769e07c8edce472327a8462b upstream.

This reverts commit 5083fd7bdfe6760577235a724cf6dccae13652c2.

A bulk-out size smaller than the end-point size is indeed valid. The
offending commit broke the usb-debug driver for EHCI debug devices,
which use 8-byte buffers.

Fixes: 5083fd7bdfe6 ("USB: serial: make bulk_out_size a lower limit")
Reported-by: "Li, Elvin" <elvin.li@intel.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>