[efi] Allow for custom methods for disconnecting existing drivers

Allow for greater control over the process used to disconnect existing
drivers from a device handle, by converting the "exclude" field from a
simple protocol GUID to a per-driver method.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/drivers/net/efi/snp.c

@@ -59,8 +59,8 @@ static int nii_supported ( EFI_HANDLE device ) {
 /** EFI SNP driver */
 struct efi_driver snp_driver __efi_driver ( EFI_DRIVER_SNP ) = {
 	.name = "SNP",
-	.exclude = &efi_simple_network_protocol_guid,
 	.supported = snp_supported,
+	.exclude = snpnet_exclude,
 	.start = snpnet_start,
 	.stop = snpnet_stop,
 };
@@ -68,8 +68,8 @@ struct efi_driver snp_driver __efi_driver ( EFI_DRIVER_SNP ) = {
 /** EFI NII driver */
 struct efi_driver nii_driver __efi_driver ( EFI_DRIVER_NII ) = {
 	.name = "NII",
-	.exclude = &efi_nii31_protocol_guid,
 	.supported = nii_supported,
+	.exclude = nii_exclude,
 	.start = nii_start,
 	.stop = nii_stop,
 };