firmware/dmc/icl: Add missing MODULE_FIRMWARE() for Icelake.

Add missing MODULE_FIRMWARE while loading DMC ICL.

v2: Add Fixes tag. (Rodrigo)
v3: Rebase by Rodrigo after commit 7fe78985cd ("drm/i915/csr:
 restructure CSR firmware definition macros")
v4: Rodrigo fixing his own mess on commit mentioning on v3
    comment above.

Fixes: 4445930f1c ("firmware/dmc/icl: load v1.07 on icelake.")
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com> (v2)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Tested-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181004223613.19938-1-rodrigo.vivi@intel.com
(cherry picked from commit 00e5d8b1eb)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

drivers/gpu/drm/i915/intel_csr.c

@@ -35,6 +35,7 @@
  */
 
 #define I915_CSR_ICL "i915/icl_dmc_ver1_07.bin"
+MODULE_FIRMWARE(I915_CSR_ICL);
 #define ICL_CSR_VERSION_REQUIRED	CSR_VERSION(1, 7)
 
 #define I915_CSR_GLK "i915/glk_dmc_ver1_04.bin"