x86: math-emu: Drop already-disabled print of build date

The kernel already has this information, so other bits of kernel code
shouldn't duplicate that.  This also eliminates the use of __DATE__,
which makes the build non-deterministic.

This message was already disabled at build time, with PRINT_MESSAGES
undef'd at the top of the file.

Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Michal Marek <mmarek@suse.cz>