include: llce: Add LLCE UART interrupts

commit 1e450822e30316b764a09bf28e6b135db14e3f01 from
https://github.com/nxp-auto-linux/linux

LLCE UART channels share same intterupt. As a concequence, LLCE mailbox
becames an intterupt controller and LLCE Linflex nodes will use the
intterupts defined in this header.

Issue: ALB-10318
Signed-off-by: Larisa Grigore <larisa.grigore@nxp.com>
Signed-off-by: Zhantao Tang <zhantao.tang@windriver.com>