[DRIVERS] mmc: Reduce delays in SD and MMC card detections

Currently, __sd_send_op_cond() and __mmc_send_op_cond() are used by
__mmc_detect_card_inserted() to detect SD and MMC cards respectively.

These functions have huge trial counts (or "timeout" counts) hence on
some ARM host (such as Raspberry Pi) we might spend lot of time trying
to detect card when no card is present.

This patch make trial counts (or "timeout" counts) in these functions
to more realistic value.

Signed-off-by: Anup Patel <anup@brainfault.org>