Fix logical bugs around access() POSIX call

According to docs of access():
If the specified access is permitted, access() returns 0.
If the given file cannot be accessed in the specified way, access() returns -1

See my comment: https://android-review.googlesource.com/c/platform/bootable/recovery/+/883392/comments/e9b76d97_f4cab88d

Test: builds
Bug: 234887937
Change-Id: I5712d61e967566246603f23a62e2c7b708130b0d