app/test: fix build with overflowed EFD value

app/test: fix build with overflowed EFD value

When RTE_EFD_VALUE_NUM_BITS is 32, there was a compilation issue
because of an overflow:

app/test/test_efd.c:157:55: error: overflow in expression;
result is 2147483647 with type 'int' [-Werror,-Winteger-overflow]
        data[0] = mrand48() & ((1 << RTE_EFD_VALUE_NUM_BITS) - 1);

This commit fixes the issue by using a setting a different
macro VALUE_BITMASK with a conditional

Fixes: 0e925aef2779 ("app/test: add EFD functional and perf tests")

Reported-by: Yong Liu <yong.liu@intel.com>
Signed-off-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>