remoteproc: elf_loader: Fix loading segment when is_iomem true

It seems luckliy work on i.MX platform, but it is wrong.
Need use memcpy_toio, not memcpy_fromio.

Fixes: 40df0a91

 ("remoteproc: add is_iomem to da_to_va")
Tested-by: Dong Aisheng <aisheng.dong@nxp.com> (i.MX8MQ)
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20210910090621.3073540-2-peng.fan@oss.nxp.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>