Blackfin arch: fix bug - kernel build fails with undefined reference to pm_overflow_handler

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>

diff --git a/arch/blackfin/Kconfig b/arch/blackfin/Kconfig
index a394957..b58af2b 100644
--- a/arch/blackfin/Kconfig
+++ b/arch/blackfin/Kconfig
@@ -1018,7 +1018,7 @@
 
 config HARDWARE_PM
 	bool "OProfile use hardware porformance monitor"
-	depends on OPROFILE
+	depends on OPROFILE=y
 	default n
 
 endmenu