convert twr_pwrlock*() to semaphore part 1

Signed-off-by: Hans Ulli Kroll <ulli.kroll@googlemail.com>
convert twr_pwrlock*() to semaphore part 2

Signed-off-by: Hans Ulli Kroll <ulli.kroll@googlemail.com>
convert twr_pwrlock*() to semaphore part 3

Signed-off-by: Hans Ulli Kroll <ulli.kroll@googlemail.com>
remove typedef struct semaphore _pwrlock

Signed-off-by: Hans Ulli Kroll <ulli.kroll@googlemail.com>
_sema -> struct semaphore

Signed-off-by: Hans Ulli Kroll <ulli.kroll@googlemail.com>
remove LINUX_VERSION

Signed-off-by: Hans Ulli Kroll <ulli.kroll@googlemail.com>
_rtw_init_sema() -> linux sema_init()

Signed-off-by: Hans Ulli Kroll <ulli.kroll@googlemail.com>
_rtw_up_sema() -> linux up()

Signed-off-by: Hans Ulli Kroll <ulli.kroll@googlemail.com>
remove unneeded _rtw_free_sema()

Signed-off-by: Hans Ulli Kroll <ulli.kroll@googlemail.com>
_rtw_down_sema() -> linux down_interruptible()

Signed-off-by: Hans Ulli Kroll <ulli.kroll@googlemail.com>
remove some LINUX_VERSION code

Signed-off-by: Hans Ulli Kroll <ulli.kroll@googlemail.com>
BIT(x) is a linux makro so use it