bnx2x: Change bnx2x_tests_str_arr to static char

This patch changes the definition of bnx2x_tests_str_arr from char to static
char. This correction will also eliminate the sparse warning created in commit
cf2c1df62e065bfc15e38daf2d3479a56b320f29.

Signed-off-by: Merav Sicron <meravs@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>