Use SYM_DATA_START_LOCAL()/SYM_DATA_END() in vgetrandom-chacha.S so
that the constants end up in an object with correct size:

readelf -Ws vgetrandom-chacha.o
   Num:    Value          Size Type    Bind   Vis      Ndx Name
   ...
     5: 0000000000000000    32 OBJECT  LOCAL  DEFAULT    5 chacha20_constants
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>