remoteproc: core: Fix cdev remove and rproc del

remoteproc: core: Fix cdev remove and rproc del

The rproc_char_device_remove() call currently unmaps the cdev
region instead of simply deleting the cdev that was added as a
part of the rproc_char_device_add() call. This change fixes that
behaviour, and also fixes the order in which device_del() and
cdev_del() need to be called.

Signed-off-by: Siddharth Gupta <sidgup@codeaurora.org>
Link: https://lore.kernel.org/r/1623723671-5517-4-git-send-email-sidgup@codeaurora.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>