remoteproc: pru: Fix loading of GNU Binutils ELF

remoteproc: pru: Fix loading of GNU Binutils ELF

[ Upstream commit e6d9423d31b2f9bdd0220fd0584e3bb6ed2c4e52 ]

PRU port of GNU Binutils lacks support for separate address spaces.
PRU IRAM addresses are marked with artificial offset to differentiate
them from DRAM addresses. Hence remoteproc must mask IRAM addresses
coming from GNU ELF in order to get the true hardware address.

PRU firmware used for testing was the example in:
  https://github.com/dinuxbg/pru-gcc-examples/tree/master/blinking-led/pru

Signed-off-by: Dimitar Dimitrov <dimitar@dinux.eu>
Link: https://lore.kernel.org/r/20201230105005.30492-1-dimitar@dinux.eu
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>