AF_RXRPC imposes a 49 char limit on UTS_RELEASE, but building with

  BUILD_NUMBER=P12345678 bazel build //common:kernel_x86_64_allmodconfig --config=stamp

requires more than 49 chars in UTS_RELEASE. Hence, this module
is disabled for allmodconfig.

Bug: 273576197
Test: ABTD
Change-Id: Ife604db109f870eda2fdbc0668d6bd1f4e4e906e
Signed-off-by: Yifan Hong <elsk@google.com>