sqm-scripts: Modify installation step to ensure correct chmod values

Use INSTALL_BIN & INSTALL_DATA macros instead of cp to ensure correct chmod values for the executable files.

I got burned with the file permissions on scripts after backporting sqm to BB14.07. Using INSTALL_BIN macro will ensure that the executable files have the executable bit set.

Signed-off-by: Hannu Nyman <hannu.nyman@iki.fi>