MicroPython needs to handle the UART idle interrupt, which is not something
that the standard SDK provides. This was previously fixed by including in
the mimxrt port a modified copy of `fsl_lpuart.c`.
This commit changes how that's done by building the unmodified
`fsl_lpuart.c` directly from the SDK, and using linker wrapping to override
the necessary functions to get at the idle IRQ. As part of this, the code
is updated to work with the latest SDK.
Signed-off-by: Andrew Leech <andrew.leech@planetinnovation.com.au>
0e9e66100e