ext: hal: nordic: Update nrfx to version 1.7.1

Updates nrfx to the recently released version. See
https://github.com/NordicSemiconductor/nrfx/blob/v1.7.1/CHANGELOG.md
for a list of changes that this version introduces.

Origin: nrfx
License: BSD 3-Clause
URL: https://github.com/NordicSemiconductor/nrfx/tree/v1.7.1


commit: 9d68726e41c321f1772c187bd12d82f5b13104f1
Purpose: Provide peripheral drivers for Nordic SoCs
Maintained-by: External

Signed-off-by: Andrzej Głąbek <andrzej.glabek@nordicsemi.no>