Documentation: devices.txt: reconcile serial/ucc_uart minor numers

Documentation: devices.txt: reconcile serial/ucc_uart minor numers

Reconcile devices.txt with serial/ucc_uart.c regarding device number
assignments. ucc_uart.c supports 4 ports and uses minor devnums
46-49, so update devices.txt with that info.
Then update ucc_uart.c's reference to the location of the devices.txt
list in the kernel source tree.

Fixes: d7584ed2b994 ("[POWERPC] qe-uart: add support for Freescale QUICCEngine UART")
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Timur Tabi <timur@kernel.org>
Cc: Kumar Gala <galak@kernel.crashing.org>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: linux-serial@vger.kernel.org
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Link: https://lore.kernel.org/r/20230724063341.28198-1-rdunlap@infradead.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>