misc: fastrpc: fix improper packet size calculation

misc: fastrpc: fix improper packet size calculation

commit 3a1bf591e9a410f220b7405a142a47407394a1d5 upstream.

The buffer list is sorted and this is not being considered while
calculating packet size. This would lead to improper copy length
calculation for non-dmaheap buffers which would eventually cause
sending improper buffers to DSP.

Fixes: c68cfb718c8f ("misc: fastrpc: Add support for context Invoke method")
Reviewed-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Jeya R <jeyr@codeaurora.org>
Link: https://lore.kernel.org/r/1637771481-4299-1-git-send-email-jeyr@codeaurora.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>