UPSTREAM: remoteproc: core: Add ops to enable custom coredump functionality

Each remoteproc might have different requirements for coredumps and might
want to choose the type of dumps it wants to collect. This change allows
remoteproc drivers to specify their own custom dump function to be executed
in place of rproc_coredump. If the coredump op is not specified by the
remoteproc driver it will be set to rproc_coredump by default.

Signed-off-by: Siddharth Gupta <sidgup@codeaurora.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>

Bug: 180426943
Change-Id: I0ce93a43298172e8b5b9ebcd9c51b9beaa1d5eeb
(cherry picked from commit adf60a87)
Signed-off-by: Siddharth Gupta <quic_sidgup@quicinc.com>