package/libinput: fix build with libevdev

libevdev and libinput use the same function name (log_msg).
An easy fix is to rename one of the two functions.

Fixes:
http://autobuild.buildroot.net/results/b1e/b1ea94f09d6f7459e3d7794c4a62bbdbb53d5da6/build-end.log



[Thomas: slightly reword the patch description.]

Signed-off-by: Romain Naour <romain.naour@openwide.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>