{bp-15353} fix compile error

[jerpelea]

Summary

chip/efm32_leserial.c: In function 'efm32_restoreuartint': Error: chip/efm32_leserial.c:329:37: error: 'len' undeclared (first use in this function); did you mean 'ien'?
329 | efm32_restoreuartint_nolock(priv, len);
| ^~~
| ien

Impact

RELEASE

Testing

CI

[nuttxpr]

[Experimental Bot, please feedback here]

No, this PR does not meet the NuttX requirements. The provided information only describes a build error, not the intended change. It's missing crucial information:

• Missing context/purpose: What was the original intent of the change that introduced this error? A bug fix? A new feature? What problem is being solved?
• Missing "how it works": The summary needs to describe the intended change, not just the error message. How should efm32_restoreuartint work? What was the logic behind the modification that led to the undeclared len variable?
• Incomplete Impact Assessment: "RELEASE" is insufficient. While it suggests this impacts a release, it doesn't detail how. Which architectures or boards are affected? Does it change any user-facing behavior? Does it introduce any compatibility issues?
• No Testing Information: "CI" is also inadequate. CI (Continuous Integration) is a process, not a result. The PR needs to show actual test results, logs demonstrating the issue before the change and the corrected behavior after the change. It should also specify the host build environment and the target platform. Providing build logs with the error doesn't count as testing the intended functionality.

The PR needs to be revised to provide the missing context, explain the intended change, and include proper testing logs demonstrating the fix. Just fixing the compiler error isn't enough; the PR must demonstrate that the fix achieves the desired outcome without introducing regressions.