efi_loader: use logging for bootefi command

Log messages of the bootefi command instead of simply printing them to the
console.

Do not show "## Application terminated" message when the UEFI binary
completed successfully.

Adjust the python tests testing for '## Application terminated'.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/test/py/tests/test_efi_fit.py b/test/py/tests/test_efi_fit.py
index 06fb151..068a35a 100644
--- a/test/py/tests/test_efi_fit.py
+++ b/test/py/tests/test_efi_fit.py
@@ -420,12 +420,11 @@
             fit_config = 'config-efi-fdt' if enable_fdt else 'config-efi-nofdt'
 
             # Try booting.
-            cons.run_command(
-                'bootm %x#%s' % (addr, fit_config), wait_for_prompt=False)
+            output = cons.run_command('bootm %x#%s' % (addr, fit_config))
             if enable_fdt:
-                cons.wait_for('Booting using the fdt blob')
-            cons.wait_for('Hello, world')
-            cons.wait_for('## Application terminated, r = 0')
+                assert 'Booting using the fdt blob' in output
+            assert 'Hello, world' in output
+            assert '## Application failed' not in output
             cons.restart_uboot()
 
     cons = u_boot_console