crypto: vmx - VMX crypto should depend on CONFIG_VSX

crypto: vmx - VMX crypto should depend on CONFIG_VSX

This code uses FP (floating point), Altivec and VSX (Vector-Scalar
Extension). It can just depend on CONFIG_VSX though, because that
already depends on FP and Altivec.

Otherwise we get lots of link errors such as:

  drivers/built-in.o: In function `.p8_aes_setkey':
  aes.c:(.text+0x2d325c): undefined reference to `.enable_kernel_altivec'
  aes.c:(.text+0x2d326c): undefined reference to `.enable_kernel_vsx'

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>