Fix wrong bpp value when drawing radio buttons

[nroggeman-ledger]

Description

The goal of this PR is to fix wrong bpp value set when drawing radio buttons. It was forced to 1BPP but radio buttons can be 1, 2 or 4 BPP

Changes include

• [*] Bugfix (non-breaking change that solves an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (change that is not backwards-compatible and/or changes current functionality)
• Tests
• Documentation
• Other (for changes that might not fit in any category)

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 71.42857% with 2 lines in your changes missing coverage. Please review.

Project coverage is 60.20%. Comparing base (44b02b4) to head (9d30e84).

Files	Patch %	Lines
lib_nbgl/src/nbgl_obj.c	71.42%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #725      +/-   ##
==========================================
+ Coverage   60.19%   60.20%   +0.01%     
==========================================
  Files          12       12              
  Lines        1726     1729       +3     
==========================================
+ Hits         1039     1041       +2     
- Misses        687      688       +1     

Flag	Coverage Δ
unittests	60.20% <71.42%> (+0.01%)	⬆️

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