arch/xtensa: Add non-HAL caching primitives

The Xtensa L1 cache layer has straightforward semantics accessible via
single-instructions that operate on cache lines via physical
addresses.  These are very amenable to inlining.

Unfortunately the Xtensa HAL layer requires function calls to do this,
leading to significant code waste at the calling site, an extra frame
on the stack and needless runtime instructions for situations where
the call is over a constant region that could elide the loop.  This is
made even worse because the HAL library is not built with
-ffunction-sections, so pulling in even one of these tiny cache
functions has the effect of importing a 1500-byte object file into the
link!

Add our own tiny cache layer to include/arch/xtensa/cache.h and use
that instead.

Signed-off-by: Andy Ross <andrew.j.ross@intel.com>

soc/xtensa/intel_adsp/common/soc_mp.c

@@ -18,6 +18,7 @@
 LOG_MODULE_REGISTER(soc_mp, CONFIG_SOC_LOG_LEVEL);
 
 #include <soc.h>
+#include <arch/xtensa/cache.h>
 #include <adsp/io.h>
 
 #include <soc/shim.h>
@@ -125,7 +126,7 @@ void z_mp_entry(void)
 	 * isn't using yet.  Manual inspection of generated code says
 	 * we're safe, but really we need a better solution here.
 	 */
-	xthal_dcache_all_writeback_inv();
+	z_xtensa_cache_flush_inv_all();
 
 	/* Copy over VECBASE from the main CPU for an initial value
 	 * (will need to revisit this if we ever allow a user API to