tty: serial: Use "no_log" readl/writel variants in hsl_read/write

hsl_read and hsl_write both directly call ioread32/iowrite32, which
leads to either a __raw_readl or __raw_writel call. These
readl/writel call are logged to the register trace buffer (RTB) by
default and generate a very large amount of output. This patch
directly calls __raw_readl_no_log and __raw_writel_no_log in
hsl_read and hsl_write to avoid logging these events to the RTB.

Change-Id: I9b3253996188f0642a4f6dedf449ec23fa1de05a
Signed-off-by: David Garibaldi <dgaribal@codeaurora.org>