USB: storage: ene_ub6250: Use macros for firmware names

Advertise firmware files using MODULE_FIRMWARE macros.

Fix a debug string: SD_RDWR_PATTERN --> SD_RW_PATTERN

Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>