soc/intel/apl: Fix building with clang & LTO

LTO does not like that assert on a constant, so use the more appropriate
static assertion.

Change-Id: I52094ec825fcec56a9b9fb6b9abc58644c2bf9cb
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/84047
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Sean Rhodes <sean@starlabs.systems>
Reviewed-by: Nico Huber <nico.h@gmx.de>

src/soc/intel/apollolake/romstage.c

@@ -319,7 +319,7 @@ void platform_fsp_memory_init_params_cb(FSPM_UPD *mupd, uint32_t version)
 		mrc_cache_current_mmap_leak(MRC_VARIABLE_DATA, version,
 					    NULL);
 
-	assert(CONFIG(BOOT_DEVICE_MEMORY_MAPPED));
+	_Static_assert(CONFIG(BOOT_DEVICE_MEMORY_MAPPED), "Boot device not memory mapped");
 
 	fsp_version = version;
 }