If CONFIG_OF_PLATDATA=y , then the udevice has no valid OF node associated
with it and ofnode_valid(node) evaluates to 0. The dev_read_u32_default()
call ultimately reaches ofnode_read_u32_index() which invokes fdt_getprop()
and passes result of ofnode_to_offset(node) as an offset parameter into it.
The ofnode_to_offset(node) returns -1 for invalid node, which leads to an
fdt_getprop(..., -1, ...) invocation, which will crash sandbox with SIGSEGV
because libfdt can not handle negative node offsets without full tree check,
which U-Boot inhibits to keep size lower.
Since i2c_child_post_bind() already calls dev_has_ofnode(dev), reuse the
same call and assign i2c->speed_hz = I2C_SPEED_STANDARD_RATE in case the
device has no valid node associated with it, and do not call any of the
dev_read_*() functions for devices without valid nodes.
Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>