[Bug] oled_write_raw overruns data buffer, corrupts display when cursor not at origin (0, 0)

[bcat]

Describe the Bug

The oled_write_raw function reads from the data buffer and copies to oled_buffer, but it incorrectly offsets reads from data if the oled_cursor isn't at the start of the buffer. This means it reads beyond the end of the data buffer and corrupts the display.

PR #10800 updated oled_write_raw and oled_write_raw_P to respect the cursor position, but it looks like it also introduced this bug. It only happens for the non-PROGMEM variant of the function, which I suspect is why it hasn't been caught before. (Most folks probably use the PROGMEM variant on AVR boards, but I'm on an ARM board where oled_write_raw_P is just an alias for oled_write_raw.)

The fix is straightforward enough: use the oled_cursor offset for the write to oled_buffer, but not the read from data.

System Information

• Keyboard: Unicorne (not yet merged, Add a new keyboard "Unicorne" #12993)
  • Revision (if applicable): f411
• Operating system: Debian Buster on WSL2 (Linux wiggin 5.4.72-microsoft-standard-WSL2 #1 SMP Wed Oct 28 23:40:43 UTC 2020 x86_64 GNU/Linux)
• AVR GCC version: avr-gcc (GCC) 5.4.0

• ARM GCC version: arm-none-eabi-gcc (15:7-2018-q2-6) 7.3.1 20180622 (release) [ARM/embedded-7-branch revision 261907]

• QMK Firmware version: 0.13.2

• Any keyboard related software installed?
  • AutoHotKey
  • Karabiner
  • Other:

Additional Context