Remove redundant guard clauses

[veyndan]

The subsequent guard clauses validate the expression in the same way:

val resolvedCall = expression.getResolvedCall(bindingContext) ?: return
if (uselessFqNames.contains(resolvedCall.resultingDescriptor.fqNameOrNull()))

[codecov]

Codecov Report

Merging #2919 into master will increase coverage by 0.00%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master    #2919   +/-   ##
=========================================
  Coverage     80.23%   80.23%           
+ Complexity     2449     2446    -3     
=========================================
  Files           421      421           
  Lines          7406     7402    -4     
  Branches       1355     1352    -3     
=========================================
- Hits           5942     5939    -3     
  Misses          764      764           
+ Partials        700      699    -1     

Impacted Files	Coverage Δ	Complexity Δ
...urbosch/detekt/rules/style/UselessCallOnNotNull.kt	80.95% <ø> (+0.95%)	5.00 <0.00> (-3.00)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 9e14c7b...f686c8f. Read the comment docs.