Remove unnecessary HIP_TARGETS validation in CMake

Author: vlad-perevezentsev

CMakeLists.txt

@@ -103,17 +103,13 @@ if ("x${DPNP_SYCL_TARGETS}" STREQUAL "x")
         else()
             set(_dpnp_sycl_targets "amdgcn-amd-amdhsa,spir64-unknown-unknown")
         endif()
-    elseif (DEFINED HIP_TARGETS AND "x${HIP_TARGETS}" STREQUAL "x")
-        message(FATAL_ERROR "HIP_TARGETS must be specified when using HIP backend")
     endif()
 else()
     set(_dpnp_sycl_targets ${DPNP_SYCL_TARGETS})
 
     if (NOT "x${HIP_TARGETS}" STREQUAL "x")
         set(_dpnp_amd_targets ${HIP_TARGETS})
         set(_use_onemkl_interfaces_hip ON)
-    elseif (DEFINED HIP_TARGETS AND "x${HIP_TARGETS}" STREQUAL "x")
-        message(FATAL_ERROR "HIP_TARGETS must be specified when using HIP backend")
     endif()
 endif()