avb: Fix build when CONFIG_OPTEE_TA_AVB is disabled

When having only these AVB related configs enabled:

    CONFIG_AVB_VERIFY=y
    CONFIG_CMD_AVB=y
    CONFIG_LIBAVB=y

build fails with next errors:

    common/avb_verify.c: In function 'read_persistent_value':
    common/avb_verify.c:867:6: warning: implicit declaration of function
                                        'get_open_session'
    common/avb_verify.c:870:45: error: 'struct AvbOpsData' has no member
                                        named 'tee'
    common/avb_verify.c:894:7: warning: implicit declaration of function
                                        'invoke_func'
    common/avb_verify.c: In function 'write_persistent_value':
    common/avb_verify.c:931:45: error: 'struct AvbOpsData' has no member
                                       named 'tee'

Guard read_persistent_value() and write_persistent_value() functions
by checking if CONFIG_OPTEE_TA_AVB is enabled (as those are only used in
that case) to fix the build with mentioned configuration.

Signed-off-by: Sam Protsenko <[email protected]>
Reviewed-by: Igor Opaniuk <[email protected]>

common/avb_verify.c

@@ -851,6 +851,7 @@ static AvbIOResult get_size_of_partition(AvbOps *ops,
 	return AVB_IO_RESULT_OK;
 }
 
+#ifdef CONFIG_OPTEE_TA_AVB
 static AvbIOResult read_persistent_value(AvbOps *ops,
 					 const char *name,
 					 size_t buffer_size,
@@ -968,6 +969,8 @@ static AvbIOResult write_persistent_value(AvbOps *ops,
 
 	return rc;
 }
+#endif
+
 /**
  * ============================================================================
  * AVB2.0 AvbOps alloc/initialisation/free