ice: fix security issue with validating error in pointer

get_ice_device_from_storage_type can return error pointer which is
not NULL in case of error, this was not checked, changes fix this.

Change-Id: I7dd8a068454a7bd250189ff9467c685af449f81b
Signed-off-by: Andrey Markovytch <andreym@codeaurora.org>