[Offload] Re-enable tests that are now passing

Summary:
Some recent patches made these stop failing so the XFAIL now makes the
bots go red.

Fixes https://github.com/llvm/llvm-project/issues/98903

offload/test/api/omp_dynamic_shared_memory_amdgpu.c

@@ -2,7 +2,6 @@
 // RUN: env LIBOMPTARGET_SHARED_MEMORY_SIZE=256 \
 // RUN:   %libomptarget-run-amdgcn-amd-amdhsa | %fcheck-amdgcn-amd-amdhsa
 // REQUIRES: amdgcn-amd-amdhsa
-// XFAIL: amdgcn-amd-amdhsa
 
 #include <omp.h>
 #include <stdio.h>

offload/test/api/omp_dynamic_shared_memory_mixed_amdgpu.c

@@ -2,7 +2,6 @@
 // RUN: env LIBOMPTARGET_NEXTGEN_PLUGINS=1 \
 // RUN:   %libomptarget-run-amdgcn-amd-amdhsa | %fcheck-amdgcn-amd-amdhsa
 // REQUIRES: amdgcn-amd-amdhsa
-// XFAIL: amdgcn-amd-amdhsa
 
 #include "omp_dynamic_shared_memory_mixed.inc"
 // CHECK: PASS

offload/test/offloading/bug51982.c

@@ -1,7 +1,6 @@
 // RUN: %libomptarget-compile-generic -O1 && %libomptarget-run-generic
 // -O1 to run openmp-opt
 // RUN: %libomptarget-compileopt-generic -O1 && %libomptarget-run-generic
-// XFAIL: amdgcn-amd-amdhsa
 
 int main(void) {
   long int aa = 0;