package/mariadb: fix potential error message in sysv startup script

package/mariadb: fix potential error message in sysv startup script

In order to check if the initial database needs created, the startup
script calls ls -1 $MYSQL_LIB | wc -l to check the number of files in
the directory. If the directory does not exist, an error is printed.
We fix this by redirecting stderr to /dev/null for the ls call.

Signed-off-by: Ryan Coe <bluemrp9@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>