package/linux-serial-test: bump version

This update fixes both the below mentioned build error when handling
undefined baud rates, and makes the patch for MIPS obsolete.

No other changes will be introduced with this update.

Fixes:
http://autobuild.buildroot.net/results/ef77cbe220619050eb9d46c78ae79a94eea8aa8b



Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>