vold: resolve crypto device creation failure with dm-crypt

Crypto device creation fails if 'system: vold: FDE target boot'
is picked on top of 'system: vold: pass proper extra params to load
crypto device'. The extra params passed to dm-crypt driver were NULL
causing the mapped device creation failure.
If 'system: vold: FDE target boot'is not picked device mapper
creation with dm-req-crypt fails. So fix the issue for both device mapper
drivers with passing correct param type while loading crypto table.

CRs-Fixed: 2457311
Change-Id: If66a7034659e6971fb2ba8c89c5e28186ca43cb4