target-mips: Replace macros by inline functions

target-mips: Replace macros by inline functions

The macros RESTORE_ROUNDING_MODE and RESTORE_FLUSH_MODE silently used
variable env from their callers. Using inline functions with env passed
as a function argument is more transparent.

This modification was proposed by Peter Maydell.

Cc: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Stefan Weil <sw@weilnetz.de>
Reviewed-by: Eric Johnson <ericj@mips.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>