staging: pi433: Added information about bit_rate configuration

Information in the TODO file for bit_rate configuration is
insufficient.

This patch adds information on how to approach when considering
to modify bit_rate to support upto 300kbps.
Signed-off-by: Guru Mehar Rachaputi <gurumeharrachaputi@gmail.com>
Acked-by: Dan Carpenter <error27@gmail.com>
Link: https://lore.kernel.org/r/Y9laj+z0TuasBRx5@combine-ThinkPad-S1-YogaSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/pi433/TODO

@@ -3,3 +3,6 @@
 * Some missing data (marked with ###) needs to be added in the documentation
 * Change (struct pi433_tx_cfg)->bit_rate to be a u32 so that we can support
     bit rates up to 300kbps per the spec.
+  -> This configuration needs to be moved to sysfs instead of being done through
+     IOCTL. Going forward, we need to port userspace tools to use sysfs instead
+     of IOCTL and then we would delete IOCTL.