xen: Adjust break/fallthrough statements

sh_destroy_shadow() has a spelling of fallthrough which doesn't match the
permitted pattern.  Convert it to a real fallthrough (psedo)keyword.

Elsewhere, insert breaks at the end of the default statements.

No functional change.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
Reviewed-by: Michal Orzel <michal.orzel@amd.com>

xen/arch/arm/pci/pci-access.c

@@ -63,6 +63,7 @@ int pci_generic_config_read(struct pci_host_bridge *bridge, pci_sbdf_t sbdf,
         break;
     default:
         ASSERT_UNREACHABLE();
+        break;
     }
 
     return 0;
@@ -89,6 +90,7 @@ int pci_generic_config_write(struct pci_host_bridge *bridge, pci_sbdf_t sbdf,
         break;
     default:
         ASSERT_UNREACHABLE();
+        break;
     }
 
     return 0;

xen/arch/arm/pci/pci-designware.c

@@ -48,6 +48,7 @@ static int dw_pcie_read(void __iomem *addr, unsigned int len, uint32_t *val)
         break;
     default:
         ASSERT_UNREACHABLE();
+        break;
     }
 
     return 0;
@@ -71,6 +72,7 @@ static int dw_pcie_write(void __iomem *addr, unsigned int len, uint32_t val)
         break;
     default:
         ASSERT_UNREACHABLE();
+        break;
     }
 
     return 0;

xen/arch/arm/tee/optee.c

@@ -1206,6 +1206,7 @@ static void do_call_with_arg(struct optee_domain *ctx,
     default:
         /* Free any temporary shared buffers */
         free_shm_buffers(ctx, call->xen_arg);
+        break;
     }
 
     put_std_call(ctx, call);

xen/arch/x86/mm/shadow/common.c

@@ -1213,7 +1213,7 @@ void sh_destroy_shadow(struct domain *d, mfn_t smfn)
 #ifdef CONFIG_PV32
     case SH_type_l2h_64_shadow:
         ASSERT(is_pv_32bit_domain(d));
-        /* Fall through... */
+        fallthrough;
 #endif
     case SH_type_l2_64_shadow:
         SHADOW_INTERNAL_NAME(sh_destroy_l2_shadow, 4)(d, smfn);