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/plat/arm/board/fvp/fvp_el3_spmc.c b/plat/arm/board/fvp/fvp_el3_spmc.c
index 2b347ed..6b44f63 100644
--- a/plat/arm/board/fvp/fvp_el3_spmc.c
+++ b/plat/arm/board/fvp/fvp_el3_spmc.c
@@ -18,7 +18,7 @@
 
 #define PLAT_SPMC_SHMEM_DATASTORE_SIZE 512 * 1024
 
-__section("arm_el3_tzc_dram") static uint8_t
+__section(".arm_el3_tzc_dram") static uint8_t
 plat_spmc_shmem_datastore[PLAT_SPMC_SHMEM_DATASTORE_SIZE];
 
 int plat_spmc_shmem_datastore_get(uint8_t **datastore, size_t *size)