crypto: octeontx2 - remove CONFIG_DM_CRYPT check

No issues were found while using the driver with dm-crypt enabled. So
CONFIG_DM_CRYPT check in the driver can be removed.

This also fixes the NULL pointer dereference in driver release if
CONFIG_DM_CRYPT is enabled.

...
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000008
...
Call trace:
 crypto_unregister_alg+0x68/0xfc
 crypto_unregister_skciphers+0x44/0x60
 otx2_cpt_crypto_exit+0x100/0x1a0
 otx2_cptvf_remove+0xf8/0x200
 pci_device_remove+0x3c/0xd4
 __device_release_driver+0x188/0x234
 device_release_driver+0x2c/0x4c
...

Fixes: 6f03f0e8 ("crypto: octeontx2 - register with linux crypto framework")
Signed-off-by: Shijith Thotton <sthotton@marvell.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>