As the location counter seems to keep counting from the VMA addresses
(in the writable_data MEMORY), manually compute the linker variable to
ensure that it points to the actual end of the binary, in the image
MEMORY.
Bug: 238050226
Test: atest vmbase_example.integration_test
Change-Id: I00616aaebee82a82e2860ce22966a40e374d49c0