drm/i915/guc: Replace %phn with %ph

%phn is not a valid specifier, and the trailing 'n' is being eaten by
the format-specifier and defaulting to the ' ' separator. Avoid angering
smatch by using the unknown specifier, and use the default we expect.

drivers/gpu/drm/i915/intel_guc_ct.c:616 ctb_read() warn: '%ph' cannot be followed by 'n'
drivers/gpu/drm/i915/intel_guc_ct.c:616 ctb_read() warn: '%ph' cannot be followed by 'n'
drivers/gpu/drm/i915/intel_guc_ct.c:616 ctb_read() warn: '%ph' cannot be followed by 'n'
drivers/gpu/drm/i915/intel_guc_ct.c:669 ct_handle_response() warn: '%ph' cannot be followed by 'n'
drivers/gpu/drm/i915/intel_guc_ct.c:679 ct_handle_response() warn: '%ph' cannot be followed by 'n'
drivers/gpu/drm/i915/intel_guc_ct.c:693 ct_handle_response() warn: '%ph' cannot be followed by 'n'
drivers/gpu/drm/i915/intel_guc_ct.c:707 ct_handle_response() warn: '%ph' cannot be followed by 'n'
drivers/gpu/drm/i915/intel_guc_ct.c:727 ct_process_request() warn: '%ph' cannot be followed by 'n'
drivers/gpu/drm/i915/intel_guc_ct.c:803 ct_handle_request() warn: '%ph' cannot be followed by 'n'

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180410111417.27563-1-chris@chris-wilson.co.uk