Patch not upstream as this driver is deleted there.

Fix up some "extern inline" functions as they break the build when using
a "modern" complier (i.e. gcc5).
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Philip Müller <philm@manjaro.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>