drm/i915/selftest: Fix use of err in igt_reset_{fail, nop}_engine()

Clang warns:

In file included from drivers/gpu/drm/i915/gt/intel_reset.c:1514:
drivers/gpu/drm/i915/gt/selftest_hangcheck.c:465:62: warning: variable
'err' is uninitialized when used here [-Wuninitialized]
        pr_err("[%s] Create context failed: %d!\n", engine->name, err);
                                                                  ^~~
...
drivers/gpu/drm/i915/gt/selftest_hangcheck.c:580:62: warning: variable
'err' is uninitialized when used here [-Wuninitialized]
        pr_err("[%s] Create context failed: %d!\n", engine->name, err);
                                                                  ^~~
...
2 warnings generated.

This appears to be a copy and paste issue. Use ce directly using the %pe
specifier to pretty print the error code so that err is not used
uninitialized in these functions.

Fixes: 3a7b7266 ("drm/i915/selftest: Bump selftest timeouts for hangcheck")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210813171158.2665823-1-nathan@kernel.org