mspi: fix no buffer reset before each psram read issue
mspi: fix no buffer reset before each psram read issue

In psram timing tuning driver, we rely on psram read and write functions
defined in `spi_timing_config.c`. If we don't do buffer reset (clear to
0), the function may untouch the buffer, which will keep last time value
(since we reuse the buffer). Therefore, if the first read is expected,
but next few reads didn't modify the buffer content, we will still see
the expected data.

These functions relies on `esp_rom_opiflash_exec_cmd`.

espressif/esp-idf,espressif/esp-idf,espressif/esp-idf,espressif/esp-idf