soc: nordic: Include <nrfx.h> instead of <nrf.h> from <soc.h>

This change is done so that there is no need to additionaly include
<nrfx.h> before <soc/nrfx_coredep.h> (what might be a bit surprising)
and so that <nrfx_config.h> doesn't need to be include separately for
nRF SoCs requiring a special mapping of peripheral accessing symbols.

This commit removes also no longer needed inclusions and updates
the hal_nordic module with required minor correction of nrfx_glue.h.

Signed-off-by: Andrzej Głąbek <andrzej.glabek@nordicsemi.no>

soc/arm/nordic_nrf/nrf51/soc.h

@@ -14,7 +14,7 @@
 #ifndef _ASMLANGUAGE
 
 #include <nrf_common.h>
-#include <nrf.h>
+#include <nrfx.h>
 
 /* Add include for DTS generated information */
 #include <generated_dts_board.h>