pass: Clean-up code to remove unneded prefix (pass_res -> res)

pass: Clean-up code to remove unneded prefix (pass_res -> res)

The pass core uses the 'pass_res' variable name to indicate the instance
of 'struct pass_resource'. 'pass_' prefix is not beneficial and not necessary.
This patch alters 'pass_res' to 'res' simply and use the 'res_type' name
insted of 'id' variable name in order to improve the understanding
what is meaning of variable.

Change-Id: Idf2a2a8ea1f48d1724d40dc50488097946113d57
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>