package/quickjs: fix typo in prefix
The quickjs Makefile expects the variable PREFIX to be set [1] but
prefix is set instead.
Without this parameter quickjs is installed to /usr/local by default [2]
instead of /usr as requested.
This commit fixed this error.
[1]: https://github.com/bellard/quickjs/blob/master/Makefile#L383
[2]: https://github.com/bellard/quickjs/blob/master/Makefile#L43
Signed-off-by: Thomas Bonnefille <thomas.bonnefille@bootlin.com>
Signed-off-by: Julien Olivain <ju.o@free.fr>