Avoid false HIP error when building for default target

Author: vlad-perevezentsev

CMakeLists.txt

@@ -103,8 +103,6 @@ if ("x${DPNP_SYCL_TARGETS}" STREQUAL "x")
         else()
             set(_dpnp_sycl_targets "amdgcn-amd-amdhsa,spir64-unknown-unknown")
         endif()
-    else()
-        message(FATAL_ERROR "HIP_TARGETS must be specified when using HIP backend")
     endif()
 else()
     set(_dpnp_sycl_targets ${DPNP_SYCL_TARGETS})