feat(fwu): modify the check for getting the FWU bank's state

The version 2 of the FWU metadata structure has a field bank_state in
the top level of the structure which can be used to check if a given
bank is in the either of Trial State, Accepted State, or in an Invalid
State. This is different from the binary states of Valid/Accepted
States that the bank could be in, as defined in the earlier version of
the specification.

Replace the fwu_is_trial_run_state() API with
fwu_get_active_bank_state() to get the state the current active bank
is in. The value returned by this API is then used by the caller to
take appropriate action.

Change-Id: I764f486840a3713bfe5f8e03d0634bfe09b23590
Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
diff --git a/include/drivers/fwu/fwu.h b/include/drivers/fwu/fwu.h
index 1414fec..489d4a1 100644
--- a/include/drivers/fwu/fwu.h
+++ b/include/drivers/fwu/fwu.h
@@ -14,7 +14,7 @@
 #define FWU_BANK_STATE_INVALID		0xFFU
 
 void fwu_init(void);
-bool fwu_is_trial_run_state(void);
+uint32_t fwu_get_active_bank_state(void);
 const struct fwu_metadata *fwu_get_metadata(void);
 
 #endif /* FWU_H */