drivers: serial: esp32: Unify serial driver for esp32 & esp32s2

1) Allow use of interrup driven instance.
   ROM implementation could be selected via dts compatiable.

2) Use UART rx fifo and timeout interrupt for end of message detection.
   Added to decrease interrupts count on data reception

3) Use ESP_LL api.

Signed-off-by: Pavlo Hamov <p.hamov@venstar.com>