lbutils: remove rw on_eintr functions. just use rw

rw is enough. i unified everything there.

next commit will remove rw_type and instead
run positional i/o depending on whether the
offset is zero. i'm simplifying the API a lot.

Signed-off-by: Leah Rowe <leah@libreboot.org>

util/libreboot-utils/lib/rand.c

@@ -165,8 +165,7 @@ retry_rand: {
 	open_file_on_eintr("/dev/urandom", &fd, O_RDONLY, 0400, NULL);
 
 	while (rw_retry(saved_errno,
-		rc = read_on_eintr(fd,
-		    (unsigned char *)buf + off, n - off)));
+	    rc = rw(fd, (unsigned char *)buf + off, n - off, 0, IO_READ)));
 #elif defined(__linux__)
 	long rc;
 	while (sys_retry(saved_errno,