infiniband: hfi1: Use EFI GetVariable only when available

Replace the EFI runtime services check with one that tells us whether
EFI GetVariable() is implemented by the firmware.

Cc: Mike Marciniszyn <mike.marciniszyn@intel.com>
Cc: Dennis Dalessandro <dennis.dalessandro@intel.com>
Cc: Doug Ledford <dledford@redhat.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: linux-rdma@vger.kernel.org
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

drivers/infiniband/hw/hfi1/efivar.c

@@ -78,7 +78,7 @@ static int read_efi_var(const char *name, unsigned long *size,
 	*size = 0;
 	*return_data = NULL;
 
-	if (!efi_enabled(EFI_RUNTIME_SERVICES))
+	if (!efi_rt_services_supported(EFI_RT_SUPPORTED_GET_VARIABLE))
 		return -EOPNOTSUPP;
 
 	uni_name = kcalloc(strlen(name) + 1, sizeof(efi_char16_t), GFP_KERNEL);