Cleanup: improve readability of filter expression condition

Cleanup: improve readability of filter expression condition

In this situation, a logical inequality '!=' is equivalent to the
binary xor '^' that was used.

However, while it is equivalent, mixing logical ('!') and bitwise
operators ('^') makes this code harder to read than it needs to be.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>