Platform: Make some NV counter enums conditional

The two NV counters used by the bootloader, PLAT_NV_COUNTER_3
and PLAT_NV_COUNTER_4 are only used if BL2 is #defined, and
making them conditional on that #define adjusts PLAT_NV_COUNTER_MAX,
effectively freeing those NV counters for use elsewhere.

Change-Id: I15982c1ad085273cd2b26e66cde936f972f661a0
Signed-off-by: Chris Brand <chris.brand@cypress.com>
diff --git a/platform/include/tfm_plat_nv_counters.h b/platform/include/tfm_plat_nv_counters.h
index ff34a91..5d63399 100644
--- a/platform/include/tfm_plat_nv_counters.h
+++ b/platform/include/tfm_plat_nv_counters.h
@@ -30,8 +30,10 @@
     PLAT_NV_COUNTER_0 = 0,  /* Used by SST service */
     PLAT_NV_COUNTER_1,      /* Used by SST service */
     PLAT_NV_COUNTER_2,      /* Used by SST service */
+#ifdef BL2
     PLAT_NV_COUNTER_3,      /* Used by bootloader */
     PLAT_NV_COUNTER_4,      /* Used by bootloader */
+#endif
     PLAT_NV_COUNTER_MAX
 };