crypto: mips/poly1305 - add missing MODULE_DESCRIPTION() macro

With ARCH=mips, make allmodconfig && make W=1 C=1 reports:
WARNING: modpost: missing MODULE_DESCRIPTION() in arch/mips/crypto/poly1305-mips.o

Add the missing invocation of the MODULE_DESCRIPTION() macro.

Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>