kbuild: disable sparse warning "returning void-valued expression"
kbuild: disable sparse warning "returning void-valued expression"

The sparse warning -Wreturn-void ("returning void-valued expression")
is off by default, but it is enabled with -Wall, so add
-Wno-return-void to CHECKFLAGS to disable it.

Signed-off-by: Hannes Eder <331be22c6b63ca3e0a03d408c2d906b1b02cd5f2@hanneseder.net>
Signed-off-by: Sam Ravnborg <f16bed56189e249fe4ca8ed10a1ecae60e8ceac0@ravnborg.org>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas