[Bug Fixed] Correct the number of output channels of LFF in RDB

[ryanxingql]

Motivation

When using the RDB, I found this bug.

The RDB adopts residual learning between x and self.lff(self.layers(x)). However, the channel number of x is in_channels, while the output channels of self.lff is channel_growth.

This bug did not cause error in the past because the default channel_growth of the RDN class is 64, which is not indicated in any config files of RDN. At the same time, all config files use mid_channels=64, which is equal to the channel_growth.

However, when someone uses the RDB class independently, this bug may cause error.

Issue: #1136

Modification

I change the number of output channels of LFF from channel_growth to in_channels.

Who can help? @ them here!

@plyfager

Checklist

Before PR:

• I have read and followed the workflow indicated in the CONTRIBUTING.md to create this PR.
• Pre-commit or linting tools indicated in CONTRIBUTING.md are used to fix the potential lint issues.
• Bug fixes are covered by unit tests, the case that causes the bug should be added in the unit tests.
• New functionalities are covered by complete unit tests. If not, please add more unit test to ensure the correctness.
• The documentation has been modified accordingly, including docstring or example tutorials.

After PR:

• If the modification has potential influence on downstream or other related projects, this PR should be tested with some of those projects.
• CLA has been signed and all committers have signed the CLA in this PR.