ARM: mvebu: Fix broken PL310_ERRATA_753970 selects

The MACH_ARMADA_375 and MACH_ARMADA_38X boards select ARM_ERRATA_753970,
but it was renamed to PL310_ERRATA_753970 by commit fa0ce403 ("ARM:
7162/1: errata: tidy up Kconfig options for PL310 errata workarounds").

Fix the selects to use the new name.

Discovered with the
https://github.com/ulfalizer/Kconfiglib/blob/master/examples/list_undefined.py


script.
Fixes: fa0ce403 ("ARM: 7162/1: errata: tidy up Kconfig options for
PL310 errata workarounds"
cc: stable@vger.kernel.org
Signed-off-by: Ulf Magnusson <ulfalizer@gmail.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>