dt-bindings: cache: bt1-l2-ctl: Remove unused bindings

dt-bindings: cache: bt1-l2-ctl: Remove unused bindings

As stated in [1] the Baikal platforms are not supported and
the respective driver code has just been removed. Remove
unused bindings.

Link: https://lore.kernel.org/lkml/22b92ddf-6321-41b5-8073-f9c7064d3432@infradead.org/
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20260225173930.3819351-3-andriy.shevchenko@linux.intel.com
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>