misc: at25: Switch to use BIT() instead of custom approaches

It's obvious that custom approach of getting power of 2 number with
int_pow() kinda interesting. Replace it and some others approaches
by using a simple BIT() operation.

Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20211125213203.86693-7-andriy.shevchenko@linux.intel.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>