drm/i915: Fix i915_error_state_store error defination

Since commit 742379c0 ("drm/i915: Start chopping up the GPU error
capture"), function 'i915_error_state_store' was defined and used with
only one parameter.

But if no 'CONFIG_DRM_I915_CAPTURE_ERROR', this function was defined
with two parameter.

This may lead compile error. This patch fix it.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com>
Reviewed-by: Andi Shyti <andi.shyti@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20200117073436.6507-1-zhangxiaoxu5@huawei.com