Simplify ctrl, shift, alt mods detection for Massdrop CTRL

[foxx1337]

This is just an "aesthetic" change, to use more modern code for detecting the states of the main modifiers.

Description

Makes use of the MOD_MASK_ macros instead of the expanded expressions when dealing with the modifier keys.

Others should be able to see this and incorporate it in their own Massdrop layouts. The old model was:

#define MODS_SHIFT  (get_mods() & MOD_BIT(KC_LSHIFT) || get_mods() & MOD_BIT(KC_RSHIFT))
#define MODS_CTRL  (get_mods() & MOD_BIT(KC_LCTL) || get_mods() & MOD_BIT(KC_RCTRL))
#define MODS_ALT  (get_mods() & MOD_BIT(KC_LALT) || get_mods() & MOD_BIT(KC_RALT))

vs

#define MODS_SHIFT  (get_mods() & MOD_MASK_SHIFT)
#define MODS_CTRL   (get_mods() & MOD_MASK_CTRL)
#define MODS_ALT    (get_mods() & MOD_MASK_ALT)

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Keyboard (addition or update)
• Keymap/layout/userspace (addition or update)
• Documentation

Issues Fixed or Closed by This PR

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

Suggested by @ash0x0 at #8692.

[vomindoraan]

LGTM

[ridingqwerty]

LGTM

[zvecr]

Thanks!