ARM: versatile: Fix typo in versatile.c

Corrected minor typo in versatile.c
- Fixed "documentaton" to "documentation"

Signed-off-by: Shivam Chaudhary <cvam0000@gmail.com>
Acked-by: Liviu Dudau <liviu.dudau@arm.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
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SoC folks: Please apply this patch directly.