test/py: Add option to skip SPL signature checking

Provide user option to skip SPL signature verification for cases where
u-boot is build with SPL support but full U-Boot is also verified
without SPL.

If you want to support this feature please add env__spl_skipped = True
to your boardenv configuration file.

For example Xilinx Zynq is using this feature where the same U-Boot
binary is checked with SPL and without SPL(with FSBL).

Signed-off-by: Michal Simek <michal.simek@xilinx.com>

test/py/u_boot_console_base.py

@@ -307,7 +307,9 @@ class ConsoleBase(object):
             config_spl = bcfg.get('config_spl', 'n') == 'y'
             config_spl_serial_support = bcfg.get('config_spl_serial_support',
                                                  'n') == 'y'
-            if config_spl and config_spl_serial_support:
+            env_spl_skipped = self.config.env.get('env__spl_skipped',
+                                                  False)
+            if config_spl and config_spl_serial_support and not env_spl_skipped:
                 m = self.p.expect([pattern_u_boot_spl_signon] +
                                   self.bad_patterns)
                 if m != 0: