all: Drop unnecessary access mode patches

Due to a change in atdf2svd [1], all these access mode patches are no
longer required - they are now translated correctly from the vendor
source file.

Drop all patches which no longer change the output (the code before and
after this change is equivalent when using the new atdf2svd).

[1]: https://github.com/Rahix/atdf2svd/commit/a189276b3540b647fab832946edf0acf39730a0e

fix: atmegaX8 TIFR should be read-write

patch: Restructure timer patches

Redesign timer patch file structure for better modularity.  Now,
`timer/<chip>.yaml` defines all timer peripherals for a chip and uses
peripheral-level includes for patching the actual peripheral.  The
actual peripheral patches live in `timer/dev/<type>.yaml`.

The intermediate `<chip>.yaml` file is needed because peripheral-level
includes are not allowed in top-level files.

Signed-off-by: Rahix <rahix@rahix.de>

common: Fix a few patches

- Fix some descriptions
- Rename ambiguous WDT options

atmega32u4, attiny85: Add tc0 patch

Signed-off-by: Rahix <rahix@rahix.de>