BACKPORT: hw_breakpoint: Allow watchpoint of length 3,5,6 and 7

(cherry picked from commit 651be3cb085341a21847e47c694c249c3e1e4e5b)

We only support breakpoint/watchpoint of length 1, 2, 4 and 8. If we can
support other length as well, then user may watch more data with less
number of watchpoints (provided hardware supports it). For example: if we
have to watch only 4th, 5th and 6th byte from a 64 bit aligned address, we
will have to use two slots to implement it currently. One slot will watch a
half word at offset 4 and other a byte at offset 6. If we can have a
watchpoint of length 3 then we can watch it with single slot as well.

ARM64 hardware does support such functionality, therefore adding these new
definitions in generic layer.

Signed-off-by: Pratyush Anand <panand@redhat.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Pavel Labath <labath@google.com>
[pavel: tools/include/uapi/linux/hw_breakpoint.h is not present in this branch]
Change-Id: Ie17ed89ca526e4fddf591bb4e556fdfb55fc2eac
Bug: 30919905