Fix RP2040 SPI pin validation

[kbx81]

What does this implement/fix?

Quick fix to correct pins usable for SPI1

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 @clydebarrow, @esphome/core, mind taking a look at this pull request as it has been labeled with an integration (spi) 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 ✅

Project coverage is 53.63%. Comparing base (4d8b5ed) to head (8cabd1d).
Report is 18 commits behind head on dev.

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #6277      +/-   ##
==========================================
- Coverage   53.70%   53.63%   -0.08%     
==========================================
  Files          50       50              
  Lines        9408     9421      +13     
  Branches     1654     1658       +4     
==========================================
  Hits         5053     5053              
- Misses       4056     4068      +12     
- Partials      299      300       +1     

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