qcacmn: Add reduction limit to qdf_flex_mem

Add the ability to prevent qdf_flex_mem_pool from freeing memory
segments unless there are more than some minimum number in the pool
already.

Change-Id: I20bde2ed629b97924ea71b4f7f46a2c1fc1bab28
CRs-Fixed: 2229511
diff --git a/qdf/Kbuild b/qdf/Kbuild
index 2c1225b..3463afd 100644
--- a/qdf/Kbuild
+++ b/qdf/Kbuild
@@ -45,6 +45,7 @@
 linux/src/qdf_threads.o     \
 linux/src/qdf_trace.o \
 linux/src/qdf_file.o \
+src/qdf_flex_mem.o \
 src/qdf_parse.o \
 src/qdf_str.o \
 src/qdf_types.o