uniphier: simplify GZIP compress rule
uniphier: simplify GZIP compress rule

It is not necessary to read data from stdin.  The input file name
is ripped off by -n option, anyway.  I still use the redirect for
the output to specify the output file name.

Signed-off-by: Masahiro Yamada <378b411a8a63ecc7605ec4272234862d7781c6ae@socionext.com>

achingupta/arm-trusted-firmware,achingupta/arm-trusted-firmware