add missing _Val suffix on arguments to GCLK_GENCTRL_SRC()

[rlcamp]

without the suffix, the value is erroneously being shifted twice, which happens to be harmless in these particular instances because the shift is by zero

[Copilot]

Pull Request Overview

This PR fixes a bug where clock source constants were missing the _Val suffix when passed to the GCLK_GENCTRL_SRC() macro, causing double shifting of values. The fix ensures proper clock configuration by using the correct constant values.

• Adds _Val suffix to clock source constants in macro calls
• Fixes potential double-shifting issue in clock generator configuration

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[hathach]

right, thank you