crypto: caam - fix LS1021A support on ARMv7 multiplatform kernel

When built using multi_v7_defconfig, driver does not work on LS1021A:
[...]
caam 1700000.crypto: can't identify CAAM ipg clk: -2
caam: probe of 1700000.crypto failed with error -2
[...]

It turns out we have to detect at runtime whether driver is running
on an i.MX platform or not.

Cc: <stable@vger.kernel.org>
Fixes: 6c3af955 ("crypto: caam - add support for LS1021A")
Signed-off-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>