virt: sevguest: Add CONFIG_CRYPTO dependency

virt: sevguest: Add CONFIG_CRYPTO dependency

This driver fails to link when CRYPTO is disabled, or in a loadable
module:

  WARNING: unmet direct dependencies detected for CRYPTO_GCM
  WARNING: unmet direct dependencies detected for CRYPTO_AEAD2
    Depends on [m]: CRYPTO [=m]
    Selected by [y]:
    - SEV_GUEST [=y] && VIRT_DRIVERS [=y] && AMD_MEM_ENCRYPT [=y]

x86_64-linux-ld: crypto/aead.o: in function `crypto_register_aeads':

Fixes: fce96cf04430 ("virt: Add SEV-SNP guest driver")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230117171416.2715125-1-arnd@kernel.org