AL2 5.15 Compile ENA driver with PHC flag

Allow PHC functionality by setting ENA_PHC_INCLUDE=1
in the compilation flags.

Signed-off-by: David Arinzon <darinzon@amazon.com>

Author: davidarinzon

drivers/amazon/net/ena/Makefile

@@ -15,8 +15,6 @@ ifdef TEST_AF_XDP
 	ccflags-y += -DENA_TEST_AF_XDP
 endif
 
-ifdef ENA_PHC_INCLUDE
-	ccflags-y += -DENA_PHC_INCLUDE
-endif
+ccflags-y += -DENA_PHC_INCLUDE
 
 ccflags-y += -include $(srctree)/drivers/amazon/net/ena/config.h