tty: serial: fsl_lpuart: Fix a build error duplicate label 'failed_get_rs485'

Since commit 16933268 ("Merge branch 'v5.15/standard/base'
into v5.15/standard/nxp-sdk-5.15/nxp-soc") merge conflicts,
so remove duplicate failed_get_rs485, since commit 7ef67d38
("fsl_lpuart: Don't enable interrupts too early") has failed_irq_request
moved the location, so delete the redundant goto failed_irq_request.

Signed-off-by: Xiaolei Wang <xiaolei.wang@windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>