BACKPORT qed: Fix copying 2 strings

BACKPORT qed: Fix copying 2 strings

The strscpy() was a recent fix (net: qed: use correct strncpy() size) to
prevent passing the length of the source buffer to strncpy() and guarantee
null termination.
It misses the goal of overwriting only the first 3 characters in
"???_BIG_RAM" and "???_RAM" while keeping the rest of the string.
Use strncpy() with the length of 3, without null termination.

Signed-off-by: Denis Bolotin <denis.bolotin@cavium.com>
Signed-off-by: Michal Kalderon <michal.kalderon@cavium.com>