AOSP: erofs-utils: mkfs: remove block list implementation

The current Android doesn't use this method.  Let's remove it
for simplicity, as it's difficult to verify its functionality
without setuping the Android environment.

Cc: Kelvin Zhang <zhangkelvin@google.com>
Reviewed-by: Sandeep Dhavale <dhavale@google.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250406112735.348328-1-hsiangkao@linux.alibaba.com