Remove unnecessary local variable in kdbus tests

Remove unnecessary local variable in kdbus tests

[  230s] kdbus-test.c: In function 'main':
[  230s] kdbus-test.c:972:31: error: declaration of 't' shadows a previous local [-Werror=shadow]
[  230s]   972 |      const struct kdbus_test *t = &tests[i];
[  230s]       |                               ^
[  230s] kdbus-test.c:892:6: note: shadowed declaration is here
[  230s]   892 |  int t, ret = 0;
[  230s]       |      ^
[  230s] cc1: all warnings being treated as errors

Change-Id: I688feaa00630509363718f2d871adec3c2b951c7
Signed-off-by: Hyotaek Shim <hyotaek.shim@samsung.com>