sscall: Ensure we have proper exit values
sscall: Ensure we have proper exit values

We should normally be using EXIT_SUCCESS/EXIT_FAILURE but
the err()/errx() macros don't currently use that so be consistent
and use 0/1 throughout.

Signed-off-by: Dimitris Papastamos <a91262282f71bb8488398dcc9202f777d0206664@opensource.wolfsonmicro.com>

Drakevr/sscall,Drakevr/sscall