Fix xl9535 pin reads

[jesserockz]

What does this implement/fix?

Digital reads were incorrect because it was not checking per bit, but just against the pin number itself

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Other

Related issue or feature (if applicable): fixes

Pull request in esphome-docs with documentation (if applicable): esphome/esphome-docs#

Test Environment

• ESP32
• ESP32 IDF
• ESP8266
• RP2040
• BK72xx
• RTL87xx

Example entry for config.yaml:

# Example config.yaml

Checklist:

• The code change is tested and works locally.
• Tests have been added to verify that the new code works (under tests/ folder).

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated in esphome-docs.

[probot-esphome]

Hey there @mreditor97, mind taking a look at this pull request as it has been labeled with an integration (xl9535) you are listed as a code owner for? Thanks!
_{^{(message by CodeOwnersMention)}}

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (342fb72) 53.70% compared to head (1f9457f) 53.70%.

Additional details and impacted files

@@           Coverage Diff           @@
##              dev    #6242   +/-   ##
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  Coverage   53.70%   53.70%           
=======================================
  Files          50       50           
  Lines        9408     9408           
  Branches     1654     1654           
=======================================
  Hits         5053     5053           
  Misses       4056     4056           
  Partials      299      299           

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