fix(cpus): fix a typo in errata doc

Commit@af5ae9a73f67dc8c9ed493846d031b052b0f22a0
Adding a Cortex-A720-AE erratum 3699562 has a typo in CPU name
for the errata, it is for Cortex-A720-AE but had incorrectly
mentioned as Cortex-A715_AE.

Change-Id: I2332a3fcaf56a7aaab5a04e3d40428cc746d2d46
Signed-off-by: Govindraj Raja <govindraj.raja@arm.com>
1 file changed