firmware: imx: Remove IMX_SC_RPC_SVC_ABORT

This is not used by linux and not supported as part of imx SCU api, it
was added by mistake.

The constant value "9" has since been reassigned in firmware to a
different service.

Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>