CMakeLists: Remove EMU_ARCH_BITS definition

This was only ever used by the now-removed memory_util functions. Also,
given we don't plan to support 32-bit architectures, this is just a
leftover from citra at this point.

CMakeLists.txt

@@ -178,10 +178,6 @@ endif()
 set_property(DIRECTORY APPEND PROPERTY
     COMPILE_DEFINITIONS $<$<CONFIG:Debug>:_DEBUG> $<$<NOT:$<CONFIG:Debug>>:NDEBUG>)
 
-
-math(EXPR EMU_ARCH_BITS ${CMAKE_SIZEOF_VOID_P}*8)
-add_definitions(-DEMU_ARCH_BITS=${EMU_ARCH_BITS})
-
 # System imported libraries
 # ======================