evm: update empty hash check for storage state

[fedekunze]

Closes: #XXX

Description

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For contributor use:

• Targeted PR against correct branch (see CONTRIBUTING.md)
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Code follows the module structure standards.
• Wrote unit and integration tests
• Updated relevant documentation (docs/) or specification (x/<module>/spec/)
• Added relevant godoc comments.
• Added a relevant changelog entry to the Unreleased section in CHANGELOG.md
• Re-reviewed Files changed in the Github PR explorer

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For admin use:

• Added appropriate labels to PR (ex. WIP, R4R, docs, etc)
• Reviewers assigned
• Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)

[codecov]

Codecov Report

Merging #1016 (d6024fb) into main (70d5294) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #1016   +/-   ##
=======================================
  Coverage   59.15%   59.15%           
=======================================
  Files          79       79           
  Lines        6539     6539           
=======================================
  Hits         3868     3868           
  Misses       2453     2453           
  Partials      218      218           

Impacted Files	Coverage Δ
x/evm/types/storage.go	100.00% <100.00%> (ø)