android: intel/isl: remove redundant building rules

android: intel/isl: remove redundant building rules

Fixes the following building error:

including ./external/mesa/Android.mk ...
build/core/base_rules.mk:183: *** external/mesa/src/intel:
MODULE.TARGET.STATIC_LIBRARIES.libmesa_isl_tiled_memcpy already defined by external/mesa/src/intel.
make: *** [build/core/ninja.mk:164: out/build-android_x86_64.ninja] Error 1

ISL_TILED_MEMCPY_FILES is isl/isl_tiled_memcpy_normal.c
and that source file includes isl_tiled_memcpy.c source

Fixes: 96bb328 ("iris: add Android build")
Signed-off-by: Mauro Rossi <issor.oruam@gmail.com>
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>