staging: fbtft: use strncpy instead of strcpy

Using strcpy() is a security risk as the destination buffer size is not
checked and we may over-run the buffer. Use strncpy() instead, while
mentioning the buffer size leaving place for the NULL termination.

Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>