EGL: Fix ARM assembly constraint.

addne takes immed_8r (constraint I) as the second operand, not
FlexOffset (constraint J). Details:
https://gcc.gnu.org/onlinedocs/gcc/Machine-Constraints.html

Bug: 77455035
Test: Built and ran some CTS tests on Pixel XL.
Change-Id: I95588462d885274b1e7900415d5853864292c11d