ARM: 6712/1: SPEAr: replace readl(), writel() with relaxed versions in uncompress.h

readl() and writel() calls the outer cache maintainance operations
which are not available during Linux uncompression. This patch replaces
readl() and writel() with readl_relaxed() and writel_relaxed() to avoid
the link time errors.

Reviewed-by: Stanley Miao <stanley.miao@windriver.com>
Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>