crypto: xts - Add softdep on ecb

The xts module needs ecb to be present as it's meant to work
on top of ecb. This patch adds a softdep so ecb can be included
automatically into the initramfs.

Reported-by: rftc <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

crypto/xts.c

···
 MODULE_DESCRIPTION("XTS block cipher mode");
 MODULE_ALIAS_CRYPTO("xts");
 MODULE_IMPORT_NS(CRYPTO_INTERNAL);
+MODULE_SOFTDEP("pre: ecb");