build: always prefix section names with `.`

Some of our specialized sections are not prefixed with the conventional
period. The compiler uses input section names to derive certain other
section names (e.g. `.rela.text`, `.relacpu_ops`), and these can be
difficult to select in linker scripts when there is a lack of a
delimiter.

This change introduces the period prefix to all specialized section
names.

BREAKING-CHANGE: All input and output linker section names have been
 prefixed with the period character, e.g. `cpu_ops` -> `.cpu_ops`.

Change-Id: I51c13c5266d5975fbd944ef4961328e72f82fc1c
Signed-off-by: Chris Kay <chris.kay@arm.com>
diff --git a/lib/psci/psci_common.c b/lib/psci/psci_common.c
index 8d736cc..f233be1 100644
--- a/lib/psci/psci_common.c
+++ b/lib/psci/psci_common.c
@@ -55,7 +55,7 @@
  ******************************************************************************/
 non_cpu_pd_node_t psci_non_cpu_pd_nodes[PSCI_NUM_NON_CPU_PWR_DOMAINS]
 #if USE_COHERENT_MEM
-__section("tzfw_coherent_mem")
+__section(".tzfw_coherent_mem")
 #endif
 ;