Remove dashes from image names: 'BL3-x' --> 'BL3x'

This patch removes the dash character from the image name, to
follow the image terminology in the Trusted Firmware Wiki page:

    https://github.com/ARM-software/arm-trusted-firmware/wiki

Changes apply to output messages, comments and documentation.

non-ARM platform files have been left unmodified.

Change-Id: Ic2a99be4ed929d52afbeb27ac765ceffce46ed76
diff --git a/include/lib/cpus/aarch64/cpu_macros.S b/include/lib/cpus/aarch64/cpu_macros.S
index 72c35fb..f34f078 100644
--- a/include/lib/cpus/aarch64/cpu_macros.S
+++ b/include/lib/cpus/aarch64/cpu_macros.S
@@ -46,7 +46,7 @@
 CPU_RESET_FUNC: /* cpu_ops reset_func */
 	.space  8
 #endif
-#if IMAGE_BL31 /* The power down core and cluster is needed only in BL3-1 */
+#if IMAGE_BL31 /* The power down core and cluster is needed only in BL31 */
 CPU_PWR_DWN_CORE: /* cpu_ops core_pwr_dwn */
 	.space  8
 CPU_PWR_DWN_CLUSTER: /* cpu_ops cluster_pwr_dwn */