misc: fastrpc: Add support to get DSP capabilities

Add support to get DSP capabilities. The capability information is cached
on driver.

Signed-off-by: Jeya R <jeyr@codeaurora.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20220214161002.6831-4-srinivas.kandagatla@linaro.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>