rpm: update 4.18.0 -> 4.18.1

Drop:
0001-docs-do-not-build-manpages-requires-pandoc.patch
(pandoc is now detected from $PATH)
fifofix.patch
(upstream fixed the issue)

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>