drivers: spi: esp32xx: Fix CS reset over split transaction

In the case where a transaction is spilt due to the rx buff len
being longer than the tx or the transaction buffer exceeding the
size of the requested buffer with non gpio CS, the chip select
would be de-asserted/asserted in the middle of the transaction.

Fixes: #57577

Signed-off-by: Dean Sellers <dsellers@evos.com.au>