efi/libstub: Stop parsing arguments at "--"

Arguments after "--" are arguments for init, not for the kernel.

Cc: <stable@vger.kernel.org>
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20200725155916.1376773-1-nivedita@alum.mit.edu
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

drivers/firmware/efi/libstub/efi-stub-helper.c

@@ -201,6 +201,8 @@ efi_status_t efi_parse_options(char const *cmdline)
 		char *param, *val;
 
 		str = next_arg(str, &param, &val);
+		if (!val && !strcmp(param, "--"))
+			break;
 
 		if (!strcmp(param, "nokaslr")) {
 			efi_nokaslr = true;