crypto: poly1305 - cleanup stray CRYPTO_LIB_POLY1305_RSIZE

When CRYPTO_LIB_POLY1305 is unset, CRYPTO_LIB_POLY1305_RSIZE
is still set in the Kconfig, cluttering things.

Fix this by making CRYPTO_LIB_POLY1305_RSIZE depend on
CRYPTO_LIB_POLY1305.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>