[HIP][cmake] Simplify UNIX related code (the beginning)

[REASONS]
1. Make OS-dependent code more clear and readable
2. To ease Windows support

CMakeLists.txt

@@ -163,11 +163,14 @@ if(NOT CMAKE_BUILD_TYPE)
 endif()
 
 # Determine HIP install path
-if(CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT AND CMAKE_INSTALL_PREFIX MATCHES "/usr/local")
+if (UNIX)
+    set(HIP_DEFAULT_INSTALL_PREFIX "/opt/rocm/hip")
+endif()
+if(CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT)
     if(CMAKE_BUILD_TYPE MATCHES Debug)
         set(CMAKE_INSTALL_PREFIX ${CMAKE_CURRENT_SOURCE_DIR} CACHE PATH "Installation path for HIP" FORCE)
     elseif(CMAKE_BUILD_TYPE MATCHES Release)
-        set(CMAKE_INSTALL_PREFIX "/opt/rocm/hip" CACHE PATH "Installation path for HIP" FORCE)
+        set(CMAKE_INSTALL_PREFIX ${HIP_DEFAULT_INSTALL_PREFIX} CACHE PATH "Installation path for HIP" FORCE)
     else()
         message(FATAL_ERROR "Invalid CMAKE_BUILD_TYPE specified. Valid values are Debug and Release")
     endif()