Move drawRoundRect back to max-sdk-o greylist.

The API was dark grey listed in P, and it was inadvertantly moved on the
max-sdk-p greylist in commit 01053cd7.

We should not make greylist APIs less restrictive between letter
releases as this makes the situation confusing for developers.

Test: m
Bug: 123987101
Change-Id: I2b8675c7e15479a6e8121976329fec88558f8cad