boards: ti: Add support for new board lp_em_cc2340r5

Product URL: https://www.ti.com/tool/LP-EM-CC2340R5
Quick Start Guide: https://www.ti.com/lit/ml/swru588a/swru588a.pdf



Signed-off-by: Lars Thalian Morstad <l-morstad@ti.com>
Signed-off-by: Vebjorn Myklebust <v.myklebust@ti.com>
Signed-off-by: Stoyan Bogdanov <sbogdanov@baylibre.com>
Signed-off-by: Julien Panis <jpanis@baylibre.com>