util/kconfig: Uprev to Linux 5.17's kconfig

Another upstream refactoring, another local patch gone!

TEST=`util/abuild/abuild -C` output (build.h and build.conf) remains
the same

Change-Id: I0f99dcbd8ecc7256551f0a6e2c83c060cb1999b6
Signed-off-by: Patrick Georgi <patrick@coreboot.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/66046
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Elyes Haouas <ehaouas@noos.fr>

util/kconfig/preprocess.c

@@ -141,7 +141,7 @@ static char *do_lineno(int argc, char *argv[])
 static char *do_shell(int argc, char *argv[])
 {
 	FILE *p;
-	char buf[256];
+	char buf[4096];
 	char *cmd;
 	size_t nread;
 	int i;