feat(gpt): configure memory size protected by bitlock

This patch adds support in GPT library for configuration
of the memory block size protected by one bit of 'bitlock'
structure. Build option 'RME_GPT_BITLOCK_BLOCK' defines the
number of 512MB blocks covered by each bit. This numeric
parameter must be a power of 2 and can take the values from
0 to 512. Setting this value to 0 chooses a single spinlock
for all GPT L1 table entries. The default value is set to 1
which corresponds to 512MB per bit.

Change-Id: I710d178072894a3ef40daebea701f74d19e8a3d7
Signed-off-by: AlexeiFedorov <Alexei.Fedorov@arm.com>
diff --git a/make_helpers/defaults.mk b/make_helpers/defaults.mk
index e742d6c..a5c78ae 100644
--- a/make_helpers/defaults.mk
+++ b/make_helpers/defaults.mk
@@ -139,6 +139,9 @@
 # For Chain of Trust
 GENERATE_COT			:= 0
 
+# Default number of 512 blocks per bitlock
+RME_GPT_BITLOCK_BLOCK		:= 1
+
 # Default maximum size of GPT contiguous block
 RME_GPT_MAX_BLOCK		:= 2