Add support for dynamic UUID list

This module is a generic test component, which doesn't contain any
specific code for a specific SP. Therefore having the compatible SP
UUIDs hardcoded is a drawback. This commit enables defining the UUIDs
(which can be bound to this driver) when loading the module. Example:

insmod arm-ffa-user.ko uuid_str_list=\
"d9df52d5-16a2-4bb2-9aa4-d26d3b84e8c0",\
"dc1eef48-b17a-4ccf-ac8b-dfcff7711b14"

Signed-off-by: Balint Dobszay <balint.dobszay@arm.com>
Change-Id: I5861ac2c1d8f1d8c6704b1abb3a44391d4834568