The qemu_icache_linesize, qemu_icache_linesize_log,
qemu_dcache_linesize, and qemu_dcache_linesize_log variables are not
used in many files.  Move them out of osdep.h to a new
qemu/cacheinfo.h, and document them.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220208200856.3558249-5-peter.maydell@linaro.org