[boards] Fix off-by-one in SysTick cyclesPerTick

[SAY-5]

Fixes #38.

Cortex-M SysTick reloads every LOAD + 1 cycles, so cyclesPerTick must be clock / ticks_per_second - 1 to produce the intended period. All ten board configs were one cycle high, causing the 1 kHz tick to run slightly slow.

Applied the maintainer-suggested fix (subtract 1 in each board config) rather than baking the offset into systick.c, to preserve the "cyclesPerTick" naming and keep RVR writes literal.

[AlexLanzano]

Hey @SAY-5,

Thank you so much for the contribution. I just merged some changes that caused some conflicts in your PR. The SysTick device initialization has moved to the board.h instead of the board.c now so it should be a quick fix for you.

Also, prior to merging this you will need to sign the wolfSSL contributor agreement. It's a quick process, just send an email to support at wolfssl dot com to get started. Please include this PR number and tell us about your project!

[SAY-5]

Thanks for the heads up. Rebased onto main and moved the off-by-one fix into the WHAL_CFG_SYSTICK_DEV macro in each board.h. I'll email support to get the contributor agreement signed.