feat(fwu): simplify the assert to check for fwu init

Simplify the assert to check if the FWU subsystem has been initialised
in the fwu_is_trial_run_state function.

Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
Change-Id: I428668470ebd4b67e68777a62d5732cb96841ab9
diff --git a/drivers/fwu/fwu.c b/drivers/fwu/fwu.c
index b8b13cd..80f870b 100644
--- a/drivers/fwu/fwu.c
+++ b/drivers/fwu/fwu.c
@@ -142,7 +142,7 @@
 {
 	bool trial_run = false;
 
-	assert(is_fwu_initialized == true);
+	assert(is_fwu_initialized);
 
 	for (unsigned int i = 0U; i < NR_OF_IMAGES_IN_FW_BANK; i++) {
 		struct fwu_image_entry *entry = &metadata.img_entry[i];