revert(cpus): "Revert workaround for A77 erratum 1800714"

Reinstate the workaround introduced in commit
9bbc03a6e0608a949d66d9da6db12a455b452bfb. The cited change to the SDEN
could not be found and there are no known problems with the workaround.

Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
Change-Id: Iec9938f173e7565024aca798f224df339de90806
diff --git a/include/lib/cpus/aarch64/cortex_a77.h b/include/lib/cpus/aarch64/cortex_a77.h
index 63f155f..a9b4546 100644
--- a/include/lib/cpus/aarch64/cortex_a77.h
+++ b/include/lib/cpus/aarch64/cortex_a77.h
@@ -20,6 +20,7 @@
  ******************************************************************************/
 #define CORTEX_A77_CPUECTLR_EL1				S3_0_C15_C1_4
 #define CORTEX_A77_CPUECTLR_EL1_BIT_8			(ULL(1) << 8)
+#define CORTEX_A77_CPUECTLR_EL1_BIT_53			(ULL(1) << 53)
 
 /*******************************************************************************
  * CPU Power Control register specific definitions.