With pkg-config support available within musdk library
(from musdk-release-SDK-10.3.5.0-PR2 version),
meson option 'lib_musdk_dir' can be removed.
PKG_CONFIG_PATH environment variable should be set appropriately
to use the musdk library.
docs are updated with new musdk version and meson instructions.
Signed-off-by: Liron Himi <lironh@marvell.com>
Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>