iicread() leaks I2C bus lock on iicbus_block_read failure

Summary

iicread() acquires I2C bus with iicbus_request_bus at :253 but if iicbus_block_read fails at :263 it returns at :267 without calling iicbus_release_bus. Bus remains locked permanently making I2C bus and all devices inaccessible. Compare iicwrite() at :222-225 which always calls iicbus_release_bus regardless of error. Trigger: read against non-existent I2C address causing NACK.